Add a property to a JavaScript object using a variable as the name

Question

I m pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element    Example  const obj       jQuery itemsFromDom  each function       const element   jQuery this    const name   element attr  id     const value   element attr  value         Here is the problem   obj name   value      If itemsFromDom includes an element with an id of  myId   I want obj to have a property named  myId   The above gives me name   How do I name a property of an object using a variable using JavaScript

User · Answer

ajavascript have two type of annotation for fetching javascript Object properties:

Obj = {};

1) (.) annotation eg. Obj.id this will only work if the object already have a property with name 'id'

2) ([]) annotation eg . Obj[id] here if the object does not have any property with name 'id',it will create a new property with name 'id'.

so for below example:

A new property will be created always when you write Obj[name]. And if the property already exist with the same name it will override it.

const obj = {}
    jQuery(itemsFromDom).each(function() {
      const element = jQuery(this)
      const name = element.attr('id')
      const value = element.attr('value')
      // This will work
      obj[name]= value;
    })

User · Answer

You can even make List of objects like this   var feeTypeList           feeTypeTable  gt  tbody  gt  tr   each function  i  el        var feeType            var  ID     this  find  input id  txtFeeType    attr  id         feeType  feeTypeID         ddlTerm   val        feeType  feeTypeName         ddlProgram   val        feeType  feeTypeDescription         ddlBatch   val         feeTypeList push feeType

User · Answer

If you have object  you can make array of keys  than map through  and create new object from previous object keys  and values   Object keys myObject   map el   gt    const obj        obj el  myObject el  code   console log obj

User · Answer

With lodash  you can create new object like this   set   obj     set     key  val     Or you can set to existing object like this   var existingObj     a  1      set existingObj   a   5      existingObj will be    a  5     You should take care if you want to use dot       in your path  because lodash can set hierarchy  for example     set      a b c    d          a      b      c    d

User · Answer

objectname newProperty   value

User · Answer

const data          name   BMW       value   25641             name   Apple       value   45876               name   Benz       value   65784               name   Toyota       value   254         const obj       carsList         name   Ford       value   47563             name   Toyota       value   254          pastriesList        fruitsList         name   Apple       value   45876             name   Pineapple       value   84523          let keys   Object keys obj    result        for key of keys       let a        data    obj key        result key    a

User · Answer

Related to the subject  not specifically for jquery though  I used this in ec6 react projects  maybe helps someone   this setState       name     value        gt          console log  State updated     JSON stringify this state name               PS  Please mind the quote character

User · Answer

First we need to define key as variable and then we need to assign as key as object   for example  x000D   x000D  var data    key  dynamic key  value  dynamic value   x000D  var key   data key  x000D  var obj      key   data value  x000D  console log obj  x000D   x000D   x000D

User · Answer

There are two different notations to access object properties   Dot notation  myObj prop1 Bracket notation  myObj  prop1     Dot notation is fast and easy but you must use the actual property name explicitly   No substitution  variables  etc      Bracket notation is open ended   It uses a string but you can produce the string using any legal js code   You may specify the string as literal  though in this case dot notation would read easier  or use a variable or calculate in some way   So  these all set the myObj property named prop1 to the value Hello      quick easy-on-the-eye dot notation myObj prop1    Hello       brackets literal myObj  prop1      Hello       using a variable var x    prop1    myObj x     Hello                            calculate the accessor string in some weird way var numList    0 1 2   myObj   prop    numList 1       Hello          Pitfalls   myObj  xxxx     Hello           wrong  mixed notations  syntax fail myObj prop1     Hello           wrong  this expects a variable called prop1   tl dnr  If you want to compute or reference the key you must use bracket notation  If you are using the key explicitly  then use dot notation for simple clear code   Note  there are some other good and correct answers but I personally found them a bit brief coming from a low familiarity with JS on-the-fly quirkiness   This might be useful to some people

User · Answer

With ECMAScript 2015 you can do it directly in object declaration using bracket notation   var obj        key   value     Where key can be any sort of expression  e g  a variable  returning a value   var obj         hello     World      x   2   42     someObject getId     someVar

User · Answer

You can use this equivalent syntax   obj name    value

User · Answer

With the advent of ES2015  Object assign and computed property names the OP s code boils down to   var obj   Object assign apply       itemsFromDom  map  i  el    gt     el id   el value

User · Answer

If you want to add fields to an object dynamically  simplest way to do it is as follows     var params     key   k1   value 1    key   k2   value 2    key   k3   value 3     for i 0  i lt  params len  i        data params i  key    params i  value     This will create data object which has following fields    k1 1  k2 2  k3 3

[javascript] Add a property to a JavaScript object using a variable as the name?

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