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

You can use this equivalent syntax:

obj[name] = value

Example:

let obj = {};
obj["the_key"] = "the_value";

or with ES6 features:

let key = "the_key";
let obj = {
  [key]: "the_value",
};

in both examples, console.log(obj) will return: { the_key: 'the_value' }

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.

First we need to define key as variable and then we need to assign as key as object., for example

var data = {key:'dynamic_key',value:'dynamic_value'}
var key = data.key;
var obj = { [key]: data.value}
console.log(obj)

Related to the subject, not specifically for jquery though. I used this in ec6 react projects, maybe helps someone:

this.setState({ [`${name}`]: value}, () => {
      console.log("State updated: ", JSON.stringify(this.state[name]));
    });

PS: Please mind the quote character.

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;
    })

The 3 ways to access the object value We can output the object value by passing in the appropriate key. Because I used emoji as the key in my example, it's a bit tricky. So let's look at a easier example.

let me = {
  name: 'samantha',
};

// 1. Dot notation
me.name; // samantha

// 2. Bracket notation (string key)
me['name']; // samantha

// 3. Bracket notation (variable key)
let key = 'name';
me[key]; // samantha

know more

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 =>{
 const obj = {};
 obj[el]=myObject[el].code;
 console.log(obj);
});

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;

}