How to create number object property name dynamically using javascript with integer key?

Question

I need to generate a object with number object property using javascript new Object().

For example I want to create a object dynamically by the below format {1:"1",2:"2",3:"5"}

I tried below

var json_str=new Object();  
$([1,2,3]).each(function(i,t){
        var str="'json_str."+t+"="+t+"'";
        eval(str);
});

But it is not created object like that, if it is string value it will create.

Possible duplicate of [Is it possible to add dynamically named properties to JavaScript object?](https://stackoverflow.com/questions/1184123/is-it-possible-to-add-dynamically-named-properties-to-javascript-object) — Sebastian Simon, Nov 21 '17 at 18:36

Nina Scholz · Answer 1 · 2017-11-21T18:39:23.960

2

You could use Object.assign and map the objects.

var array = [1, 2, 3],
    object = Object.assign(...array.map(k => ({ [k]: k.toString() })));

console.log(object);

edited Nov 21 '17 at 18:39

answered Nov 21 '17 at 18:37

Nina Scholz

376,160
25
347
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Values should be strings – mhodges Nov 21 '17 at 18:38
@JustinNiessner JavaScript keys are always strings. It's not possible to have an integer key – mhodges Nov 21 '17 at 18:42
@mhodges I know. Which is why the now-deleted answer that says this isn't possible was the one I up-voted first. But it technically was wrong since you can also use `Symbol`s as keys. – Justin Niessner Nov 21 '17 at 18:43
@JustinNiessner True, you can use Symbols as keys as well, although they don't show up in `Object.keys()` or `for...in`, so they work differently than traditional string properties. But meh, semantics. – mhodges Nov 21 '17 at 18:49

score 2 · Answer 2 · answered Nov 21 '17 at 18:40

Simple JS:

let array = [1, 2, 3];
let object = {};

for (let num of array) {
  object[num] = String(num);
}

console.log(object);
console.log(Object.keys(object)); // your keys will automatically become strings too

You should avoid using eval() where-ever possible to prevent accidental injection exploits.

score 0 · Answer 3 · answered Nov 21 '17 at 18:45

0

I think you want to make this an Array, then you can push objects onto it:

var json_str=new Array();  
$([1,2,3]).each(function(i,t){
   json_str.push( { [t] : t });
});

json_str: Array(3)
0:{1: 1}
1:{2: 2}
2:{3: 3}

answered Nov 21 '17 at 18:45

AC__

51
7

How to create number object property name dynamically using javascript with integer key?

3 Answers3