Is there a way to use variable keys in a JavaScript object literal?

Question

I have code like this.

var key = "anything";   
var object = {   
    key: "key attribute"  
};

I want to know if there is a way to replace that key with "anything".

like

var object = {  
    "anything": "key attribute"     
};

Answer 1

In ES6, use computed property names.

const key = "anything";   

const object = {   
    [key]: "key attribute"
//  ^^^^^  COMPUTED PROPERTY NAME
};

Note the square brackets around key. You can actually specify any expression in the square brackets, not just a variable.

Answer 2

Yes. You can use:

var key = "anything";
var json = { };
json[key] = "key attribute";

Or simply use your second method if you have the values at hand when writing the program.

Answer 3

On modern Javascript (ECMAScript 6) you can sorround the variable with square brackets:

var key = "anything";

var json = {
    [key]: "key attribute"
};

Answer 4

This should do the trick:

var key = "anything";

var json = {};

json[key] = "key attribute";

Answer 5

Solution:

var key = "anything";

var json = {};

json[key] = "key attribute";

Answer 6

Recently needed a solution how to set cookies passing the dynamic json key values. Using the https://github.com/js-cookie/js-cookie#json, it can be done easily. Wanted to store each selected option value of user in cookie, so it's not lost in case of tab or browser shutting down.

var json = { 
        option_values : {}
    };
    $('option:selected').each(function(index, el) {
        var option = $(this);
        var optionText = option.text();
        var key = 'option_' + index;
        json.option_values[key] = optionText;
        Cookies.set('option_values', json, { expires: 7 } );
    }); 

Then you can retrieve each cookie key value on each page load using

Cookies.getJSON('option_values');

Answer 7

Closures work great for this.

function keyValue(key){
  return function(value){
    var object = {};
    object[key] = value;
    return object;
  }
}

var key = keyValue(key);
key(value);

Answer 8

Well, there isn't a "direct" way to do this...

but this should do it:

json[key] = json.key;
json.key = undefined;

Its a bit tricky, but hey, it works!