Check if a value is an object in JavaScript

Question

How do you check if a value is an object in JavaScript

User · Answer

Ready to use functions for checking

function isObject(o) {
  return null != o && 
    typeof o === 'object' && 
    Object.prototype.toString.call(o) === '[object Object]';
}

function isDerivedObject(o) {
  return !isObject(o) && 
    null != o && 
    (typeof o === 'object' || typeof o === 'function') &&
    /^\[object /.test(Object.prototype.toString.call(o));
}

// Loose equality operator (==) is intentionally used to check
// for undefined too

// Also note that, even null is an object, within isDerivedObject
// function we skip that and always return false for null

Explanation

In Javascript, null, Object, Array, Date and functions are all objects. Although, null is bit contrived. So, it's better to check for the null first, to detect it's not null.
Checking for typeof o === 'object' guarantees that o is an object. Without this check, Object.prototype.toString would be meaningless, since it would return object for everthing, even for undefined and null! For example: toString(undefined) returns [object Undefined]!

After typeof o === 'object' check, toString.call(o) is a great method to check whether o is an object, a derived object like Array, Date or a function.
In isDerivedObject function, it checks for the o is a function. Because, function also an object, that's why it's there. If it didn't do that, function will return as false. Example: isDerivedObject(function() {}) would return false, however now it returns true.
One can always change the definition of what is an object. So, one can change these functions accordingly.

Tests

_x000D_

function isObject(o) {_x000D_
  return null != o && _x000D_
    typeof o === 'object' && _x000D_
    Object.prototype.toString.call(o) === '[object Object]';_x000D_
}_x000D_
_x000D_
function isDerivedObject(o) {_x000D_
  return !isObject(o) && _x000D_
    null != o && _x000D_
    (typeof o === 'object' || typeof o === 'function') &&_x000D_
    /^\[object /.test(Object.prototype.toString.call(o));_x000D_
}_x000D_
_x000D_
// TESTS_x000D_
_x000D_
// is null an object?_x000D_
_x000D_
console.log(_x000D_
  'is null an object?', isObject(null)_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is null a derived object?', isDerivedObject(null)_x000D_
);_x000D_
_x000D_
// is 1234 an object?_x000D_
_x000D_
console.log(_x000D_
  'is 1234 an object?', isObject(1234)_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is 1234 a derived object?', isDerivedObject(1234)_x000D_
);_x000D_
_x000D_
// is new Number(1234) an object?_x000D_
_x000D_
console.log(_x000D_
  'is new Number(1234) an object?', isObject(new Number(1234))_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is new Number(1234) a derived object?', isDerivedObject(1234)_x000D_
);_x000D_
_x000D_
// is function object an object?_x000D_
_x000D_
console.log(_x000D_
  'is (new (function (){})) an object?', _x000D_
  isObject((new (function (){})))_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is (new (function (){})) a derived object?', _x000D_
  isObject((new (function (){})))_x000D_
);_x000D_
_x000D_
// is {} an object?_x000D_
_x000D_
console.log(_x000D_
  'is {} an object?', isObject({})_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is {} a derived object?', isDerivedObject({})_x000D_
);_x000D_
_x000D_
// is Array an object?_x000D_
_x000D_
console.log(_x000D_
  'is Array an object?',_x000D_
  isObject([])_x000D_
)_x000D_
_x000D_
console.log(_x000D_
  'is Array a derived object?',_x000D_
  isDerivedObject([])_x000D_
)_x000D_
_x000D_
// is Date an object?_x000D_
_x000D_
console.log(_x000D_
  'is Date an object?', isObject(new Date())_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is Date a derived object?', isDerivedObject(new Date())_x000D_
);_x000D_
_x000D_
// is function an object?_x000D_
_x000D_
console.log(_x000D_
  'is function an object?', isObject(function(){})_x000D_
);_x000D_
_x000D_
console.log(_x000D_
  'is function a derived object?', isDerivedObject(function(){})_x000D_
);

_x000D_

User · Answer

The Ramda functional library has a wonderful function for detecting JavaScript types   Paraphrasing the full function   function type val      return val     null         Null                  val     undefined    Undefined             Object prototype toString call val  slice 8  -1       I had to laugh when I realized how simple and beautiful the solution was   Example usage from Ramda documentation   R type          gt   Object  R type 1       gt   Number  R type false       gt   Boolean  R type  s        gt   String  R type null       gt   Null  R type          gt   Array  R type   A-z         gt   RegExp  R type      gt           gt   Function  R type undefined       gt   Undefined

User · Answer

var a    1  typeof a    object  a instanceof Object   true a instanceof Array   true  var b   a  1  b instanceof Object   true b instanceof Array   false  var c   null c instanceof Object   false c instanceof Array   false   I was asked to provide more details  Most clean and understandable way of checking if our variable is an object is typeof myVar  It returns a string with a type  e g   object    undefined     Unfortunately either Array and null also have a type object  To take only real objects there is a need to check inheritance chain using instanceof operator  It will eliminate null  but Array has Object in inheritance chain   So the solution is   if  myVar instanceof Object  amp  amp    myVar instanceof Array          code for objects

User · Answer

I m fond of simply    function isObject  item      return  typeof item      object   amp  amp   Array isArray item   amp  amp  item     null       If the item is a JS object  and it s not a JS array  and it s not null   if all three prove true  return true  If any of the three conditions fails  the  amp  amp  test will short-circuit and false will be returned  The null test can be omitted if desired  depending on how you use null     DOCS    http   devdocs io javascript operators typeof  http   devdocs io javascript global objects object  http   devdocs io javascript global objects array isarray  http   devdocs io javascript global objects null

User · Answer

function isObjectLike value      return value    null  amp  amp  typeof value     object       got from lodash

User · Answer

const isObject   function obj      const type   typeof obj    return type      function     type      object   amp  amp    obj         obj is shorthand for checking if obj is truthy  to filter out null

User · Answer

lodash has isPlainObject  which might be what many who come to this page are looking for  It returns false when give a function or array

User · Answer

Consider - typeof bar      object  to determine if bar is an object  Although typeof bar      object  is a reliable way of checking if bar is an object  the surprising gotcha in JavaScript is that null is also considered an object   Therefore  the following code will  to the surprise of most developers  log true  not false  to the console   var bar   null  console log typeof bar      object        logs true  As long as one is aware of this  the problem can easily be avoided by also checking if bar is null   console log  bar     null   amp  amp   typeof bar      object         logs false To be entirely thorough in our answer  there are two other things worth noting   First  the above solution will return false if bar is a function  In most cases  this is the desired behavior  but in situations where you want to also return true for functions  you could amend the above solution to be   console log  bar     null   amp  amp    typeof bar      object       typeof bar      function      Second  the above solution will return true if bar is an array  e g   if var bar         In most cases  this is the desired behavior  since arrays are indeed objects  but in situations where you want to also false for arrays  you could amend the above solution to be   console log  bar     null   amp  amp   typeof bar      object    amp  amp   toString call bar        object Array      However  there   s one other alternative that returns false for nulls  arrays  and functions  but true for objects   console log  bar     null   amp  amp   bar constructor     Object    Or  if you   re using jQuery   console log  bar     null   amp  amp   typeof bar      object    amp  amp       isArray bar      ES5 makes the array case quite simple  including its own null check   console log Array isArray bar

User · Answer

When everything else fails  I use this   var isObject   function item       return item constructor name      Object

User · Answer

My God  too much confusion in other answers   Short Answer   typeof anyVar     object   amp  amp  anyVar instanceof Object  amp  amp    anyVar instanceof Array   To test this simply run the following statements in chrome console   Case 1   var anyVar       typeof anyVar     object   amp  amp  anyVar instanceof Object  amp  amp    anyVar instanceof Array     true   Case 2   anyVar       typeof anyVar     object   amp  amp  anyVar instanceof Object  amp  amp    anyVar instanceof Array     false   Case 3   anyVar   null  typeof anyVar     object   amp  amp  anyVar instanceof Object  amp  amp    anyVar instanceof Array      false   Explanation  Okay Let s break it down  typeof anyVar     object  is returned true from three candidates -         and null   anyVar instanceof Object narrows down these candidates to two -           anyVar instanceof Array  narrows to only one -     Drum rolls please   By this you may have already learnt how to check for Array in Javascript

User · Answer

This will work  It is a function that returns true  false  or possibly null    x000D   x000D  const isObject   obj   gt  obj  amp  amp  obj constructor  amp  amp  obj constructor     Object  x000D   x000D  console log isObject          true x000D  console log isObject          false x000D  console log isObject new Function       false x000D  console log isObject new Number 123        false x000D  console log isObject null       null x000D   x000D   x000D

User · Answer

Let s define  quot object quot  in Javascript   According to the MDN docs  every value is either an object or a primitive   primitive  primitive value A data that is not an object and does not have any methods  JavaScript has 5 primitive datatypes  string  number  boolean  null  undefined   What s a primitive   3  abc  true null undefined  What s an object  i e  not a primitive    Object prototype everything descended from Object prototype  Function prototype  Object Function function C     -- user-defined functions   C prototype -- the prototype property of a user-defined function  this is not Cs prototype  new C   --  quot new quot -ing a user-defined function   Math Array prototype  arrays     quot a quot   1   quot b quot   2  -- objects created using literal notation new Number 3  -- wrappers around primitives     many other things       Object create null  everything descended from an Object create null   How to check whether a value is an object instanceof by itself won t work  because it misses two cases     oops   isObject Object prototype  - gt  false    oops   isObject Object create null   - gt  false function isObject val        return val instanceof Object      typeof x      object  won t work  because of false positives  null  and false negatives  functions      oops  isObject Object  - gt  false function isObject val        return  typeof val      object       Object prototype toString call won t work  because of false positives for all of the primitives   gt  Object prototype toString call 3   quot  object Number  quot    gt  Object prototype toString call new Number 3    quot  object Number  quot   So I use  function isObject val        if  val     null    return false       return    typeof val      function       typeof val      object           Daan s answer also seems to work  function isObject obj      return obj     Object obj      because  according to the MDN docs   The Object constructor creates an object wrapper for the given value  If the value is null or undefined  it will create and return an empty object  otherwise  it will return an object of a type that corresponds to the given value  If the value is an object already  it will return the value    A third way that seems to work  not sure if it s 100   is to use Object getPrototypeOf which throws an exception if its argument isn t an object     these 5 examples throw exceptions Object getPrototypeOf null  Object getPrototypeOf undefined  Object getPrototypeOf 3  Object getPrototypeOf  abc   Object getPrototypeOf true      these 5 examples don t throw exceptions Object getPrototypeOf Object  Object getPrototypeOf Object prototype  Object getPrototypeOf Object create null   Object getPrototypeOf     Object getPrototypeOf

User · Answer

Here s an answer with optional chaining  and perhaps the smallest isObj function for this question    x000D   x000D  const isObj   o   gt  o  constructor     Object  x000D   x000D     True for this x000D  console log isObj                 object  x000D   x000D     False for these x000D  console log isObj 0               number x000D  console log isObj                 array x000D  console log isObj  lol            string x000D  console log isObj null            null x000D  console log isObj undefined       undefined x000D  console log isObj      gt            function x000D  console log isObj Object          class x000D   x000D   x000D

User · Answer

OK  let s give you this concept first before answering your question  in JavaScript Functions are Object  also null  Object  Arrays and even Date  so as you see there is not a simple way like typeof obj      object   so everything mentioned above will return true  but there are ways to check it with writing a function or using JavaScript frameworks  OK   Now  imagine you have this object that s a real object  not null or function or array    var obj    obj1   obj1   obj2   obj2      Pure JavaScript     that s how it gets checked in angular framework function isObject obj      return obj     null  amp  amp  typeof obj      object       or     make sure the second object is capitalised  function isObject obj       return Object prototype toString call obj        object Object        or  function isObject obj        return obj constructor toString   indexOf  Object    gt  -1      or  function isObject obj        return obj instanceof Object      You can simply use one of these functions as above in your code by calling them and it will return true if it s an object   isObject obj     If you are using a JavaScript framework  they usually have prepared these kind of functions for you  these are few of them   jQuery       It returns  object  if real Object   jQuery type obj     Angular   angular isObject obj     Underscore and Lodash      NOTE  in Underscore and Lodash  functions  arrays return true as well but not null    isObject obj

User · Answer

UPDATE  This answer is incomplete and gives misleading results  For example  null is also considered of type object in JavaScript  not to mention several other edge cases  Follow the recommendation below and move on to other  quot most upvoted  and correct   answer quot   typeof yourVariable      object   amp  amp  yourVariable     null   Original answer  Try using typeof var  and or var instanceof something  EDIT  This answer gives an idea of how to examine variable s properties  but it is not a bulletproof recipe  after all there s no recipe at all   for checking whether it s an object  far from it  Since people tend to look for something to copy from here without doing any research  I d highly recommend that they turn to the other  most upvoted  and correct   answer

User · Answer

Performance Today 2020 09 26 I perform tests on MacOs HighSierra 10 13 6 on Chrome v85  Safari v13 1 2 and Firefox v80 for chosen solutions  Results  solutions C and H are fast fastest on all browsers for all cases solutions D and G are slow slowest on all browsers for all cases   Details I perform 3 tests cases for solutions A B C D E F G H I J K L M N O P Q R S T U V  for small object - you can run it HERE for big object - you can run it HERE for no object - you can run it HERE  Below snippet presents differences between solutions  Solutions A-G give proper answers for chosen cases described by Matt Fenwick  x000D   x000D     https   stackoverflow com a 14706877 860099 function A x      return x     Object x          https   stackoverflow com a 42250981 860099 function B x        return   isObject x         https   stackoverflow com a 34864175 860099 function C x        return x    null  amp  amp   typeof x      object     typeof x      function          https   stackoverflow com a 39187058 860099 function D x       return new function     return x          x        https   stackoverflow com a 39187058 860099 function E x       return function     return this     x    call x         https   stackoverflow com a 39187058 860099 function F x       Requires ECMAScript 5 or later      try       Object create x       return x     null      catch err        return false            https   stackoverflow com a 39187058 860099 function G x       Requires ECMAScript 5 or later      function Constructor        Constructor prototype   x    return Object getPrototypeOf new Constructor        x        https   stackoverflow com a 8511332 860099 function H x      return typeof x      object   amp  amp  x     null       https   stackoverflow com a 25715455 860099 function I x      return  typeof x      object   amp  amp   Array isArray x   amp  amp  x     null          https   stackoverflow com a 22482737 860099 function J x      return x instanceof Object         https   stackoverflow com a 50712057 860099 function K x        let t  JSON stringify x       return t   t 0            false        https   stackoverflow com a 13356338 860099 function L x      return Object prototype toString call x        object Object             https   stackoverflow com a 46663081 860099 function M o  strict   true      if  o     null    o     undefined        return false        const instanceOfObject   o instanceof Object    const typeOfObject   typeof o      object     const constructorUndefined   o constructor     undefined    const constructorObject   o constructor     Object    const typeOfConstructorObject   typeof o constructor      function     let r    if  strict     true        r    instanceOfObject    typeOfObject   amp  amp   constructorUndefined    constructorObject       else       r    constructorUndefined    typeOfConstructorObject         return r        https   stackoverflow com a 42250981 860099 function N x        return   type x       object         https   stackoverflow com a 34864175 860099 function O x        if  Object prototype toString call x        object Object              return false        else           var prototype   Object getPrototypeOf x           return prototype     null    prototype     Object prototype              https   stackoverflow com a 57863169 860099 function P x      while       Object prototype toString call x        object Object      if      x   Object getPrototypeOf x               null    return true   return false       https   stackoverflow com a 43289971 860099 function Q x     try      switch x constructor         case Number        case Function        case Boolean        case Symbol        case Date        case String        case RegExp          return x constructor     Object        case Error        case EvalError        case RangeError        case ReferenceError        case SyntaxError        case TypeError        case URIError          return  Object     Error   Error   x constructor      Object        case Array        case Int8Array        case Uint8Array        case Uint8ClampedArray        case Int16Array        case Uint16Array        case Int32Array        case Uint32Array        case Float32Array        case Float64Array          return  Object     Array   Array   x constructor      Object        case Object        default          return  Object     Object   Object   x constructor      Object            catch ex       return x    Object               https   stackoverflow com a 52478680 860099 function R x        return typeof x     object   amp  amp  x instanceof Object  amp  amp    x instanceof Array         https   stackoverflow com a 51458052 860099 function S x        return x    null  amp  amp  x constructor  name      Object        https   stackoverflow com a 42250981 860099 function T x        return x  constructor  toString   indexOf  Object    gt  -1        https   stackoverflow com a 43223661 860099 function U x        return x  constructor     Object        https   stackoverflow com a 46663081 860099 function V x      return x instanceof Object  amp  amp  x constructor     Object           -------------    TEST    -------------  console log  column  1 2 3 4 5 6 - 7 8 9 10 11      A B C D E F G H I J K L M N O P Q R S T U V   map f  gt  console log    f name          1 f new Date       1 f         1 f        1 f Object prototype     1 f Object create null      1 f     gt      -   1 f  abc      1 f 3     1 f true      1 f null      1 f undefined       console log   Columns legend  test cases    1  new Date    2       RegExp   3      4  Object prototype  5  Object create null   6      gt     function   7   abc   string   8  3  number   9  true  boolean  10  null 11  undefined  Rows  1   is object 0   is NOT object  Theoretically columns 1-6 should have have 1  columns 7-11 shoud have 0     x000D   lt script   src  https   code jquery com jquery-3 5 1 min js    integrity  sha256-9 aliU8dGd2tb6OSsuzixeV4y faTqgFtohetphbbj0     crossorigin  anonymous  gt  lt  script gt      lt script    src  https   cdnjs cloudflare com ajax libs lodash js 4 17 20 lodash min js     integrity  sha512-90vH1Z83AJY9DmlWa8WkjkV79yfS2n2Oxhsi2dZbIv0nC4E6m5AbH8Nh156kkM7JePmqD6tcZsfad1ueoaovww       crossorigin  anonymous  gt  lt  script gt     This shippet only presents functions used in performance tests - it not perform tests itself  x000D   x000D   x000D   And here are example results for chrome

User · Answer

Oh My God  I think this could be more shorter than ever  let see this   Short and Final code   x000D   x000D  function isObject obj  x000D    x000D      return obj    null  amp  amp  obj constructor name      Object  x000D    x000D   x000D  console log isObject         returns true x000D  console log isObject         returns false x000D  console log isObject null      returns false x000D   x000D   x000D    Explained  Return Types  typeof JavaScript objects  including null  returns  object    x000D   x000D  console log typeof null  typeof     typeof     x000D   x000D   x000D    Checking on Their constructors  Checking on their constructor property returns function with their names    x000D   x000D  console log      constructor     returns a function with name  Object  x000D  console log      constructor     returns a function with name  Array  x000D  console log  null  constructor    throws an error because null does not actually have a property x000D   x000D   x000D    Introducing Function name  Function name returns a readonly name of a function or  anonymous  for closures    x000D   x000D  console log      constructor name     returns  Object  x000D  console log      constructor name     returns  Array  x000D  console log  null  constructor name    throws an error because null does not actually have a property x000D   x000D   x000D       Note  As of 2018  Function name might not work in IE https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Function name Browser compatibility

User · Answer

direct answer is ofcourse typeof v    object  but this is terribly not useful  I wonder if the OP meant a plain dictionary     try    isdict v    return  v     undefined  amp  amp  v   null  amp  amp  typeof v    object   amp  amp  v constructor   Array  amp  amp  v constructor   Date

User · Answer

Try this  if  objectName instanceof Object    false      alert  Not an object      else     alert  An object

User · Answer

For the purpose of my code I found out this decision which corresponds with some of the answers above  ES6 variant  const checkType   o   gt  Object prototype                      toString                      call o                       replace     object s    g                           toLowerCase     ES5 variant  function checkType o      return Object prototype                      toString                      call o                       replace     object s    g                           toLowerCase       You can use it very simply  checkType          array      true checkType          object      true checkType 1       number      true checkType          string      true checkType    p       undefined      true checkType null       null      true  and so on

User · Answer

You can do this easily with toString   method of Object prototype  if Object prototype toString call variable       object Object        doSomething        or  if Object prototype toString call variable  slice 8 -1  toLowerCase       object       doSomething

User · Answer

After reading and trying out a lot of implementations  I ve noticed that very few people try to check for values like JSON  Math  document or objects with prototype chains longer than 1 step   Instead of checking the typeof of our variable and then hacking away edge-cases  I thought it d be better if the check is kept as simple as possible to avoid having to refactor when there s new primitives or native objects added that register as typeof of  object    After all  the typeof operator will tell you if something is an object to JavaScript  but JavaScript s definition of an object is too broad for most real-world scenarios  e g  typeof null      object    Below is a function that determines whether variable v is an object by essentially repeating two checks    A loop is started that continues as long as the stringified version of v is   object Object    I wanted the result of the function to be exactly like the logs below  so this is the only  objectness -criteria I ended up with  If it fails  the function returns false right away  v is replaced with the next prototype in the chain with v   Object getPrototypeOf v   but also directly evaluated after  When the new value of v is null  it means that every prototype including the root prototype  which could very well have been the only prototype inside the chain  have passed the check in the while loop and we can return true  Otherwise  a new iteration starts     x000D   x000D  function isObj  v    x000D    while       Object prototype toString call v        object Object    x000D    if      v   Object getPrototypeOf v               null  x000D    return true x000D    return false x000D    x000D   x000D  console log  FALSE    x000D  console log                       - gt     isObj      x000D  console log  null                 - gt     isObj null   x000D  console log  document             - gt     isObj document   x000D  console log  JSON                 - gt     isObj JSON   x000D  console log  function             - gt     isObj function         x000D  console log  new Date             - gt     isObj new Date     x000D  console log  RegExp               - gt     isObj       x000D   x000D  console log  TRUE    x000D  console log                       - gt     isObj      x000D  console log  new Object           - gt     isObj new Object     x000D  console log  new Object null      - gt     isObj new Object null    x000D  console log  new Object           - gt     isObj new Object  foo   bar      x000D  console log  Object prototype     - gt     isObj Object prototype   x000D  console log  Object create null   - gt     isObj Object create null    x000D  console log  Object create        - gt     isObj Object create  foo   bar      x000D  console log  deep inheritance     - gt     isObj Object create Object create  foo   bar       x000D   x000D   x000D

User · Answer

The most reasonable way to check the type of a value seems the typeof operator  The only problem is that it s horribly broken    It returns  object  for null  which belongs to Null type  It returns  function  for callable objects  which belong to Object type  It can return  almost  anything it wants for non-standard non-callable objects  For example  IE seemed to like  unknown   The only forbidden results are  function  and primitive types    typeof is only reliable for non-null primitives  So a way to check if a value is an object would be ensuring that the string returned by typeof does not correspond to a primitive  and that the object is not null  However  the problem is that a future standard could introduce a new primitive type  and our code would consider it to be an object  New types don t appear frequently  but for example ECMAScript 6 introduced the Symbol type   Therefore  instead of typeof  I only recommend approaches whose result varies depending on if the value is an object or not  The following intends to be a   Comprehensive but not exhaustive list of proper ways to test if a value belongs to the Object type    Object constructor  The Object constructor coerces the passed argument to an object  If it s already an object  the same object is returned   Therefore  you can use it to coerce the value to an object  and strictly compare that object with the original value   The following function requires ECMAScript 3  which introduced       function isObject value       Requires ECMAScript 3 or later      return Object value      value      I like this approach because it s simple and self-descriptive  and an analogous check will also work for booleans  numbers and strings  However  be aware it relies on the global Object not being shadowed nor altered  Constructors  When you instantiate a constructor  it can return a value different than the just-created instance  But that value will be ignored unless it s an object   The following function requires ECMAScript 3  which allowed constructors to return non-objects  Before ECMAScript 3 that threw an error  but try statements didn t exist back then   function isObject value       Requires ECMAScript 3 or later      return new function     return value          value      While a bit less simple than the previous example  this one does not rely on any global property  and thus might be the safest  this value  Old ECMAScript specifications required the this value to be an object  ECMAScript 3 introduced Function prototype call  which allowed to call a function with an arbitrary this value  but coerced to an object   ECMAScript 5 introduced a strict mode which removed this behavior  but in sloppy mode we still can  but arguably shouldn t  rely on it   function isObject value       Requires ECMAScript 3 or later in sloppy mode      return function     return this     value    call value        Prototype    All ordinary objects have an internal slot called   Prototype    whose value determines from which other object it inherits from  The value can only be an object or null  Therefore  you can attempt to create an object which inherits from the desired value  and check if it worked   Both Object create and Object getPrototypeOf require ECMAScript 5   function isObject value       Requires ECMAScript 5 or later      try       Object create value       return value     null      catch err        return false            function isObject value       Requires ECMAScript 5 or later      function Constructor        Constructor prototype   value    return Object getPrototypeOf new Constructor        value     Some new ECMAScript 6 ways  ECMAScript 6 introduces some new indirect ways to check is a value is an object  They use the previously seen approach to pass the value to some code which requires an object  wrapped inside a try statement to catch errors  Some hidden examples  not worth commenting   x000D   x000D  function isObject value       Requires ECMAScript 6 or later    x000D    try   x000D      Object setPrototypeOf     value   x000D      return value     null  x000D      catch err    x000D      return false  x000D      x000D    x000D   x000D   x000D     x000D   x000D  function isObject value       Requires ECMAScript 6 or later    x000D    try   x000D      new WeakSet  value    x000D      return true  x000D      catch err    x000D      return false  x000D      x000D    x000D   x000D   x000D       Note  I intentionally skipped some approaches like Object getPrototypeOf value   ES5  and Reflect methods  ES6  because they call essential internal methods which might do nasty things  e g  if value is a proxy  For safety reasons my examples only reference value without accessing it directly

User · Answer

Since there seems a lot of confusion about how to handle this problem correctly  I ll leave my 2 cents  this answer is spec compliant and produces correct results under all circumstances    Testing for primitives  undefined null boolean string number  function isPrimitive o  return typeof o    object   null    An object is not a primitive   function isObject o  return  isPrimitive o     Or alternatively   function isObject o  return o instanceof Object  function isPrimitive o  return  isObject o     Testing for any Array   const isArray  function        const arrayTypes Object create null       arrayTypes  Array   true      arrayTypes  Int8Array   true      arrayTypes  Uint8Array   true      arrayTypes  Uint8ClampedArray   true      arrayTypes  Int16Array   true      arrayTypes  Uint16Array   true      arrayTypes  Int32Array   true      arrayTypes  Uint32Array   true      arrayTypes  BigInt64Array   true      arrayTypes  BigUint64Array   true      arrayTypes  Float32Array   true      arrayTypes  Float64Array   true      return function o           if   o  return false          return  isPrimitive o  amp  amp   arrayTypes o constructor name                 Testing for object excluding  Date RegExp Boolean Number String Function any Array  const isObjectStrict  function        const nativeTypes Object create null       nativeTypes  Date   true      nativeTypes  RegExp   true      nativeTypes  Boolean   true      nativeTypes  Number   true      nativeTypes  String   true      nativeTypes  Function   true      return function o           if   o  return false          return  isPrimitive o  amp  amp  isArray o  amp  amp  nativeTypes o constructor name

User · Answer

I know it s old  but I do think this solution is interesting if you don t care about the property order   x000D   x000D  function objectsDeeplyEqual obj1  obj2    x000D    const keys1   Object keys obj1   x000D    const keys2   Object keys obj2   x000D    let equal   true  x000D    if  keys1 length     keys2 length    x000D      return false  x000D      x000D    for  let i   0  i  lt  keys1 length  amp  amp  equal  i      x000D      if  obj1 keys1 i   instanceof Object  amp  amp  obj2 keys1 i   instanceof Object    x000D        equal   equal  amp  amp  isDeeplyEqual obj1 keys1 i    obj2 keys1 i     x000D        else   x000D        equal   equal  amp  amp  obj1 keys1 i       obj2 keys1 i    x000D        x000D      x000D    return equal  x000D    x000D   x000D  var a     x000D    a  true  x000D    b   asd   x000D    c    x000D      a  true  x000D      b   asd   x000D      c    x000D        a  true  x000D        b   asd   x000D         x000D       x000D     x000D   x000D  var b     x000D    a  true  x000D    c    x000D      a  true  x000D      b   asd   x000D      c    x000D        a  true  x000D        b   asd   x000D         x000D       x000D    b   asd   x000D     x000D   x000D  console log isDeeplyEqual a b    x000D  console log isDeeplyEqual b a    x000D   x000D   x000D

User · Answer

you can just use JSON stringify to test your Object  like this    x000D   x000D  var test      x000D  if JSON stringify test  0             x000D    console log  this is a Object   x000D    x000D   x000D   x000D

User · Answer

use typeof my obj  will tells which type of variable it is    for Array  Array isArray inp  or    isinstanceof Array  if it is object will show  object   simple JS function   function isObj v        return typeof v      object      Eg    x000D   x000D  function isObj v    x000D      return typeof v      object  x000D    x000D   x000D  var samp obj     x000D      a    1  x000D      b    2  x000D      c    3 x000D    x000D   x000D  var num   10  x000D  var txt    Hello World   x000D  var collection    samp obj  num  txt  x000D  for  var i in var collection    x000D    if isObj var collection i      x000D       console log  yes it is object   x000D      x000D    else   x000D       console log  No it is    typeof var collection i    x000D      x000D    x000D   x000D   x000D

User · Answer

Mostly typeof obj index       object is used  but it will return also function and  document which are an objects  It depends up to you if it need to be included in the result   Basically you can do a test code that filtering out if a particular elements is an object by checking the output in your console  Here you can run a code just for a sample    x000D   x000D  function cekObject obj  index      x000D    if   obj tagName    x000D   x000D        test case  1       x000D      if  typeof obj      object     x000D        console log  obj    index     is listed as an object    x000D         x000D       x000D      x000D    x000D   lt script src  https   ajax googleapis com ajax libs jquery 1 2 3 jquery min js  gt  lt  script gt  x000D   lt script gt  x000D    function updateFilters     x000D      var object       j-image    x000D          juicer-feed   empty    x000D       x000D      for var index in object    x000D        cekObject object index   index   x000D          x000D      x000D   lt  script gt  x000D   x000D   lt ul class  juicer-feed  data-feed-id  chetabahana  data-after  updateFilters    gt  lt  ul gt  x000D   lt script src  https   assets juicer io embed js  gt  lt  script gt  x000D   x000D   x000D

User · Answer

It is an old question but thought to leave this here  Most people are checking if the variable is    meaning a key-value paired and not what is the underline construct that JavaScript is using for a given thing  cuz to be honest mostly everything in JavaScript is an object  So taking that out of the way  If you do     let x   function      typeof x      function    true x     Object x     true x      x     Object x     true     also x   null typeof null     object    Most of the time what we want is to know if we have a resource object from an API or our database call returned from the ORM  We can then test if is not an Array  is not null  is not typeof  function   and is an Object     To account also for new Date   as  toddmo pointed out  x instanceof Object  amp  amp  x constructor     Object  x    test     false x   3    false x   45 6    false x   undefiend    false x    undefiend     false x   null    false x   function        false x    1  2     false x   new Date      false x         true

User · Answer

i found a  new  way to do just this kind of type checking from this SO question  Why does instanceof return false for some literals   from that  i created a function for type checking as follows   function isVarTypeOf  var   type       try           return  var constructor      type        catch ex            return false            fallback for null or undefined           then you can just do   console log isVarTypeOf  asdf   String         returns true console log isVarTypeOf new String  asdf    String         returns true console log isVarTypeOf 123  String         returns false console log isVarTypeOf 123  Number         returns true console log isVarTypeOf new Date    String         returns false console log isVarTypeOf new Date    Number         returns false console log isVarTypeOf new Date    Date         returns true console log isVarTypeOf     Object         returns false console log isVarTypeOf     Array         returns true console log isVarTypeOf     Object         returns true console log isVarTypeOf     Array         returns false console log isVarTypeOf null  Object         returns false console log isVarTypeOf undefined  Object         returns false console log isVarTypeOf false  Boolean         returns true   this is tested on Chrome 56  Firefox 52  Microsoft Edge 38  Internet Explorer 11  Opera 43  edit  if you also want to check if a variable is null or undefined  you can use this instead   function isVarTypeOf  var   type       try           return  var constructor      type        catch ex            return  var     type      null and undefined are considered the same            or you can use     if you want to differentiate them          var a   undefined  b   null  console log isVarTypeOf a  undefined      returns true console log isVarTypeOf b  undefined      returns true console log isVarTypeOf a  null      returns true   update from inanc s comment  challenge accepted  D  if you want to loose compare objects you can try this way   function isVarTypeOf  var   type  looseCompare       if   looseCompare           try               return  var constructor      type            catch ex               return  var     type                  else           try              switch  var constructor                   case Number                  case Function                  case Boolean                  case Symbol                  case Date                  case String                  case RegExp                         add all standard objects you want to differentiate here                     return  var constructor      type                  case Error                  case EvalError                  case RangeError                  case ReferenceError                  case SyntaxError                  case TypeError                  case URIError                         all errors are considered the same when compared to generic Error                     return   type     Error   Error    var constructor       type                  case Array                  case Int8Array                  case Uint8Array                  case Uint8ClampedArray                  case Int16Array                  case Uint16Array                  case Int32Array                  case Uint32Array                  case Float32Array                  case Float64Array                         all types of array are considered the same when compared to generic Array                     return   type     Array   Array    var constructor       type                  case Object                  default                         the remaining are considered as custom class object  so treat it as object when compared to generic Object                     return   type     Object   Object    var constructor       type                          catch ex               return  var     type      null and undefined are considered the same                or you can use     if you want to differentiate them                     that way  you can do just like inanc s comment   isVarTypeOf new  function Foo       Object      returns false isVarTypeOf new  function Foo       Object  true      returns true   or  Foo   function      Bar   function      isVarTypeOf new Foo    Object        returns false isVarTypeOf new Foo    Object  true        returns true isVarTypeOf new Bar    Foo  true        returns false isVarTypeOf new Bar    Bar  true        returns true isVarTypeOf new Bar    Bar         returns true

User · Answer

I have a code snippet that works  I find it confusing when the whole piece of code is not given  so I just created it myself        lt  DOCTYPE html gt       lt html gt       lt body gt       lt button onclick  myFunc    gt Try it lt  button gt        lt script gt      var abc   new Number           var abc   4        this is a code variation which will give a diff alert      function myFunc             if abc  amp  amp  typeof abc      object       alert  abc is an object and does not return null value        else     alert  abc is not an object               lt  script gt        lt  body gt       lt  html gt

User · Answer

if typeof value      object   amp  amp  value constructor     Object        console log  This is an object

User · Answer

For simply checking against Object or Array without additional function call  speed   As also posted here  isArray   isArray   function a        return    a   amp  amp   a constructor     Array      console log isArray                false console log isArray     null       false console log isArray     true       false console log isArray        1       false console log isArray     str        false console log isArray                false console log isArray new Date       false console log isArray                true  isLiteralObject   - Note  use for Object literals only  as it returns false for custom objects  like new Date or new YourCustomObject  isLiteralObject   function a        return    a   amp  amp   a constructor     Object      console log isLiteralObject                false console log isLiteralObject     null       false console log isLiteralObject     true       false console log isLiteralObject        1       false console log isLiteralObject     str        false console log isLiteralObject                false console log isLiteralObject new Date       false console log isLiteralObject                true

User · Answer

With function Array isArray   function isObject o      return o     null  amp  amp  typeof o      object   amp  amp  Array isArray o      false      Without function Array isArray   Just surprised how many upvotes for wrong answers   Only 1 answer passed my tests    Here I ve created my simplified version   function isObject o      return o instanceof Object  amp  amp  o constructor     Object      As for me  it s clear and simple  and just works  Here my tests   console log isObject                      Will return  true console log isObject                      Will return  false console log isObject null                 Will return  false console log isObject                      Will return  false console log isObject function             Will return  false   ONE MORE TIME  not all answers pass this tests         In case you need to verify that object is instance of particular class you have to check constructor with your particular class  like   function isDate o      return o instanceof Object  amp  amp  o constructor     Date      simple test   var d   new Date    console log isObject d       Will return  false console log isDate d         Will return  true   As result  you will have strict and robust code     In case you won t create functions like isDate  isError  isRegExp  etc you may consider option to use this generalized functions   function isObject o      return o instanceof Object  amp  amp  typeof o constructor      function       it won t work correctly for all test cases mentioned earlier  but it s good enough for all objects  plain or constructed      isObject won t work in case of Object create null  because of internal implementation of Object create which is explained here but you can use isObject in more sophisticated implementation   function isObject o  strict   true      if  o     null    o     undefined        return false        const instanceOfObject   o instanceof Object    const typeOfObject   typeof o      object     const constructorUndefined   o constructor     undefined    const constructorObject   o constructor     Object    const typeOfConstructorObject   typeof o constructor      function     let r    if  strict     true        r    instanceOfObject    typeOfObject   amp  amp   constructorUndefined    constructorObject       else       r    constructorUndefined    typeOfConstructorObject         return r       There is already created package on npm v1 based on this implementation  And it works for all earlier described test cases

User · Answer

underscore js provides the following method to find out if something is really an object     isObject   function obj      return obj     Object obj        UPDATE  Because of a previous bug in V8 and minor micro speed optimization  the method looks as follows since underscore js 1 7 0  August 2014      isObject   function obj      var type   typeof obj    return type      function     type      object   amp  amp    obj

User · Answer

Its depends on use-case  if we do not want to allow array and functions to be an Object  we can use the underscore js builtin functions        function xyz  obj            if    isObject obj   amp  amp     isFunction obj   amp  amp     isArray obj                 now its sure that obj is an object

User · Answer

If you would like to check if the prototype for an object solely comes from Object  Filters out String  Number  Array  Arguments  etc   function isObject  n      return Object prototype toString call n        object Object        Or as a single-expression arrow function  ES6    const isObject   n   gt  Object prototype toString call n        object Object

User · Answer

What I like to use is this  function isObject  obj      return typeof obj      object            amp  amp   Array isArray obj            amp  amp  obj    null           amp  amp  obj                amp  amp    obj instanceof String       I think in most of the cases a Date must pass the check as an Object  so I do not filter dates out

User · Answer

It depends on what you mean with  is an object   If you want everything that is not a primitive  i e  things that you can set new properties on  this should do the trick   function isAnyObject value        return value    null  amp  amp   typeof value      object     typeof value      function        It excludes the primitives  plain numbers NaN Infinity  plain strings  symbols  true false  undefined and null  but should return true for everything else  including Number  Boolean and String objects   Note that JS does not define what  host  objects  such as window or console  should return when used with typeof  so those are hard to cover with a check like this   If you want to know whether something is a  plain  object  i e  it was created as a literal    or with Object create null   you might do this   function isPlainObject value        if  Object prototype toString call value        object Object              return false        else           var prototype   Object getPrototypeOf value           return prototype     null    prototype     Object prototype            Edit 2018  Because Symbol toStringTag now allows customizing the output of Object prototype toString call       the isPlainObject function above might return false in some cases even when the object started its life as a literal  Arguably  by convention an object with a custom string tag isn t exactly a plain object any more  but this has further muddied the definition of what a plain object even is in Javascript

User · Answer

The simplest way to determine if a variable is an Object or not  first  Evaluate the type of Object second  Getting an Array property from an Object must returns undefined  For example length is an Array property which does not work on Object  so  if   object instanceof Object  amp  amp   object length     undefined       here you can be sure that you have a curly bracket object

User · Answer

Little late    for  quot plain objects quot   i mean  like   x   5   y   7   i have this little snippet  function isPlainObject o       return  o     null    Array isArray o     typeof o     function     o constructor     Date                false             typeof o     object       It generates the next output  console debug isPlainObject isPlainObject      function  false console debug isPlainObject   x   6   y   16       literal object  true console debug isPlainObject 5      number  false console debug isPlainObject undefined      undefined  false console debug isPlainObject null      null  false console debug isPlainObject  a       string  false console debug isPlainObject         array   false console debug isPlainObject true      bool  false console debug isPlainObject false      bool  false  It always works for me  If will return  quot true quot  only if the type of  quot o quot  is  quot object quot   but no null  or array  or function

User · Answer

Remember guys that typeof new Date   is  quot object quot   So if you re looking for   key  value   objects  a date object is invalid  Finally then  o   gt  o  amp  amp  typeof o      object   amp  amp    o instanceof Date  is a better answer to your question in my opinion

User · Answer

If typeof yourVariable      object   it s an object or null  If you want to exclude null  just make it typeof yourVariable      object   amp  amp  yourVariable     null

User · Answer

If you are already using AngularJS then it has a built in method which will check if its an object  without accepting null     angular isObject

User · Answer

Object prototype toString call myVar  will return      object Object   if myVar is an object   object Array   if myVar is an array etc    For more information on this and why it is a good alternative to typeof  check out this article

User · Answer

var isArray function value       if Array isArray           return Array isArray value        else          return Object prototype toString call value      object Array            var isObject function value       return value     null amp  amp  isArray value   amp  amp  typeof value      object      var  val new Date  console log isObject  val     true console log Object prototype toString call  val      object Object      false

User · Answer

A little NodeJS console experiment based on the reading of Matt Fenwick s third option to his complete answer above  Just a little tweak to get true or false   The following return false for the object test    gt  if Object getPrototypeOf  v       Object prototype  console log true   else console log false    false undefined  gt  if Object getPrototypeOf 1      Object prototype  console log true   else console log false    false undefined  gt  if Object getPrototypeOf false      Object prototype  console log true   else console log false    false undefined  gt  if Object getPrototypeOf   apple        Object prototype  console log true   else console log false    false undefined   The object will return true    gt  if Object getPrototypeOf   this  10       Object prototype  console log true   else console log false    true undefined

User · Answer

If explicitly want to check if the given value is      function isObject  value     return value  amp  amp  typeof value      object   amp  amp  value constructor     Object

[javascript] Check if a value is an object in JavaScript

Ready to use functions for checking

Explanation

Tests

Examples related to javascript

Examples related to types

Examples related to javascript-objects