JavaScript - Maintain Object key value order

Question

My required object key-value(property-value) Order : {three:3,two:2,one:1}

I want last added key at top,When i add key-value dynamically the order i got is given below,

var numObj={};   
numObj["one"]=1;   
numObj["two"]=2; 
numObj["three"]=3;  
console.log(numObj) // result i get is  { one:1, three:3,two:2 }

Please any one help me to get this key-value order {three:3,two:2,one:1}

If you need to preserve an order then you need to use an Array; the order of keys in an Object is not guaranteed by design. — David Thomas
– David Thomas, Commented Jul 11, 2017 at 16:12
There is no key order in JavaScript nor is there a way to enforce one. — Alex K.
– Alex K., Commented Jul 11, 2017 at 16:12

Adam Wright · Accepted Answer · 2017-07-11 16:17:37Z

2

As the commenters point out, JavaScript objects have no defined order for iteration. However, JavaScript maps do: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Map.

let aMap = new Map();
myMap.set('AKey1', 'AValue1');
myMap.set('AKey2', 'AValue2');
myMap.set('AKey3', 'AValue3');

for (let x of aMap) {
  console.log(x[1]);
}

Will provide

AValue1
AValue2
AValue3

answered Jul 11, 2017 at 16:17

Adam Wright

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