CODEWITHSUNDEEP
javascript
Vinoth Babu
Vinoth Babu

Reputation: 6852

How To Set A JS object property name from a variable

I am in need to set a JS object property name dynamically.

for(i=1; i<3; i++) {
    var key  = i+'name';

    data = {
        key : 'name1',
    }
}

Result should be:

data = {
    1name: 'name1'
    2name: 'name1'
}

Upvotes: 217

Views: 180779

Answers (8)

chiliNUT
chiliNUT

Reputation: 19592

With ES 6, you can use variable property names with the object literal syntax, like this:

var keyName = 'myKey';
var obj = {
              [keyName]: 1
          };
obj.myKey;//1

This syntax is available in the following newer browsers:

Edge 12+ (No IE support), FF34+, Chrome 44+, Opera 31+, Safari 7.1+

(https://kangax.github.io/compat-table/es6/)

You can add support to older browsers by using a transpiler such as babel. It is easy to transpile an entire project if you are using a module bundler such as rollup or webpack.

Upvotes: 146

BorisD
BorisD

Reputation: 1824

Use a variable as an object key

let key = 'myKey';

let data = {[key] : 'name1'; }

See How to iterete on your object here

Upvotes: 42

Mark Corrigan
Mark Corrigan

Reputation: 1

Along the lines of Sainath S.R's comment above, I was able to set a js object property name from a variable in Google Apps Script (which does not support ES6 yet) by defining the object then defining another key/value outside of the object:

var salesperson = ...

var mailchimpInterests = { 
        "aGroupId": true,
    };

mailchimpInterests[salesperson] = true;

Upvotes: 0

Musa
Musa

Reputation: 97717

You'll have to use [] notation to set keys dynamically.

var jsonVariable = {};
for(i=1; i<3; i++) {        
 var jsonKey  = i+'name';
 jsonVariable[jsonKey] = 'name1';

}

Now in ES6 you can use object literal syntax to create object keys dynamically, just wrap the variable in []

var key  = i + 'name';
data = {
    [key] : 'name1',
}

Upvotes: 219

Knut Hering
Knut Hering

Reputation: 89

It does not matter where the variable comes from. Main thing we have one ... Set the variable name between square brackets "[ .. ]".

var optionName = 'nameA';
var JsonVar = {
[optionName] : 'some value'
}

Upvotes: 8

timc
timc

Reputation: 2174

This is the way to dynamically set the value

var jsonVariable = {};
for (var i = 1; i < 3; i++) {
    var jsonKey = i + 'name';
    jsonVariable[jsonKey] = 'name' + i;
}

Upvotes: 22

yednamus
yednamus

Reputation: 583

jsonVariable = {}
for(i=1; i<3; i++) {        
   var jsonKey  = i+'name';
   jsonVariable[jsonKey] = 'name1'
}

this will be similar to 

    jsonVariable = {
    1name : 'name1'
    2name : 'name1'
}

Upvotes: 1

closure
closure

Reputation: 7452

var jsonVariable = {};
for(var i=1; i < 3; i++) {
  jsonVariable[i + 'name'] = 'name' + i;        
}

Upvotes: 210

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