[javascript] Add property to an array of objects

I have an array of objects as shown below

Object {Results:Array[2]}
     Results:Array[2]
[0-1]
0:Object
       id=1     
       name: "Rick"
1:Object
       id=2     
       name:'david'

I want to add one more property named Active to each element of this array of Objects.

The final outcome should be as follows.

Object {Results:Array[2]}
     Results:Array[2]
[0-1]
0:Object
       id=1     
       name: "Rick"
       Active: "false"
1:Object
       id=2     
       name:'david'
       Active: "false"

Can someone please let me know how to achieve this.

This question is related to javascript arrays object underscore.js

The answer is


You can use the forEach method to execute a provided function once for each element in the array. In this provided function you can add the Active property to the element.

Results.forEach(function (element) {
  element.Active = "false";
});

With ES6 you can simply do:

 for(const element of Results) {
      element.Active = "false";
 }

or use map

Results.map(obj=> ({ ...obj, Active: 'false' }))

Edited to reflect comment by @adrianolsk to not mutate the original and instead return a new object for each.

Read the spec


It goes through the object as a key-value structure. Then it will add a new property named 'Active' and a sample value for this property ('Active) to every single object inside of this object. this code can be applied for both array of objects and object of objects.

   Object.keys(Results).forEach(function (key){
            Object.defineProperty(Results[key], "Active", { value: "the appropriate value"});
        });

  Object.defineProperty(Results, "Active", {value : 'true',
                       writable : true,
                       enumerable : true,
                       configurable : true});

I came up against this problem too, and in trying to solve it I kept crashing the chrome tab that was running my app. It looks like the spread operator for objects was the culprit.

With a little help from adrianolsk’s comment and sidonaldson's answer above, I used Object.assign() the output of the spread operator from babel, like so:

this.options.map(option => {
  // New properties to be added
  const newPropsObj = {
    newkey1:value1,
    newkey2:value2
  };

  // Assign new properties and return
  return Object.assign(option, newPropsObj);
});

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