best way to get the key of a key value javascript object

Question

If I have a JS object like   var foo      bar     baz      If I know that foo has that basic key value structure  but don t know the name of the key  what s the easiest way to get it  for     in    each    I hope there s something better

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I was having the same problem and this is what worked    example of an Object var person         firstName  John       lastName  Doe       age 50      eyeColor  blue        How to access a single key or value var key   Object keys person  0   var value   person firstName

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Given your Object   var foo      bar     baz      To get bar  use   Object keys foo  0    To get baz  use   foo Object keys foo  0     Assuming a single object

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iterate through key-value gracefully const obj     a  5  b  7  c  9    for  const  key  value  of Object entries obj       console log    key    value         a 5    b 7    c 9      Refer MDN

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You would iterate inside the object with a for loop   for var i in foo     alert i      alerts key   alert foo i      alerts key s value     Or  Object keys foo     forEach function eachKey key         alert key      alerts key      alert foo key       alerts value

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You can access each key individually without iterating as in   var obj     first   someVal   second   otherVal     alert Object keys obj  0       returns first alert Object keys obj  1       returns second

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for showing as a string  simply use   console log  they are      JSON stringify foo

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This is the simplest and easy way  This is how we do this    x000D   x000D  var obj      bar     baz    x000D  var key   Object keys obj  0   x000D  var value   obj key   x000D        x000D   console log  key      key     bar x000D   console log  value      value     baz x000D   x000D   x000D    Object keys   is javascript method which return an array of keys when using on objects   Object keys obj       bar     Now you can iterate on the objects and can access values like below-  Object keys obj  forEach  function key      console log obj key      baz

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I don t see anything else than for  var key in foo

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Object keys   The Object keys   method returns an array of a given object s own enumerable properties  in the same order as that provided by a for   in loop  the difference being that a for-in loop enumerates properties in the prototype chain as well    var arr1   Object keys obj     Object values   The Object values   method returns an array of a given object s own enumerable property values  in the same order as that provided by a for   in loop  the difference being that a for-in loop enumerates properties in the prototype chain as well    var arr2   Object values obj     For more please go here

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Well   each is a library construct  whereas for     in is native js  which should be better

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Since you mentioned   each    here s a handy approach that would work in jQuery 1 6    var foo     key1   bar   key2   baz         keys will be    key1    key2   var keys     map foo  function item  key      return key

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The easiest way is to just use Underscore js   keys   keys object  Retrieve all the names of the object s properties    keys  one   1  two   2  three   3      gt    quot one quot    quot two quot    quot three quot    Yes  you need an extra library  but it s so easy

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There is no way other than for     in  If you don t want to use that  parhaps because it s marginally inefficient to have to test hasOwnProperty on each iteration   then use a different construct  e g  an array of kvp s      key   key   value   value

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A one liner for you   const OBJECT          key1    value1        key2    value2        key3    value3        key4    value4      const value    value2    const key   Object keys OBJECT  Object values OBJECT  indexOf value     window console log key        key2

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If you want to get all keys  ECMAScript 5 introduced Object keys  This is only supported by newer browsers but the MDC documentation provides an alternative implementation  which also uses for   in btw    if  Object keys  Object keys   function o        if  o     Object o             throw new TypeError  Object keys called on non-object         var ret    p       for p in o  if Object prototype hasOwnProperty call o p   ret push p        return ret      Of course if you want both  key and value  then for   in is the only reasonable solution

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You can use Object keys functionality to get the keys like   const tempObjects  foo  bar    Object keys tempObjects  forEach obj  gt      console log  Key- gt   obj   value- gt   tempObjects obj

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best way to get key value of object    x000D   x000D  let obj     x000D           key1    value1   x000D           key2    value2   x000D           key3    value3   x000D           key4    value4  x000D        x000D      Object keys obj  map function k    x000D      console log  key with value    k        obj k       x000D       x000D         x000D       x000D   x000D   x000D

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use for each loop for accessing keys in Object or Maps in javascript  for key in foo      console log key    for key name in your case it will be bar    console log foo key      for key value in your case it will be baz     Note  you can also use      Object keys foo     it will give you like this output    bar

[javascript] best way to get the key of a key/value javascript object

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