How to prevent automatic sort of Object numeric property?

Question

Why I met this problem: I tried to solve an algorithm problem and I need to return the number which appeared most of the times in an array. Like [5,4,3,2,1,1] should return

Answer 1

You really can't rely on order of an object fields in JavaScript, but I can suggest to use Map (ES6/ES2015 standard) if you need to preserve order of your key, value pair object. See the snippet below:

let myObject = new Map();
myObject.set('z', 33);
myObject.set('1', 100);
myObject.set('b', 3);

for (let [key, value] of myObject) {
  console.log(key, value);
}
// z 33
// 1 100
// b 3