How to Iterate (Keys, Values) in Javascript? [Duplicate]

Question

I have a dictionary that has the format of

dictionary = {0: {object}, 1:{object}, 2:{object}}

How can I iterate through this dictionary by doing something like

for ((key, value) in dictionary) {
    //Do stuff where key would be 0 and value would be the object
}

Accepted Answer

tl;dr

In ECMAScript 2017, just call Object.entries(yourObj).
In ECMAScript 2015, it is possible with Maps.
In ECMAScript 5, it is not possible.

ECMAScript 2017

ECMAScript 2017 introduced a new Object.entries function. You can use this to iterate the object as you wanted.

'use strict';

const object = {'a': 1, 'b': 2, 'c' : 3};

for (const [key, value] of Object.entries(object)) {
  console.log(key, value);
}

Must Read

Output

a 1
b 2
c 3

ECMAScript 2015

In ECMAScript 2015, there is not Object.entries but you can use Map objects instead and iterate over them with Map.prototype.entries. Quoting the example from that page,

var myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

var mapIter = myMap.entries();

console.log(mapIter.next().value); // ["0", "foo"]
console.log(mapIter.next().value); // [1, "bar"]
console.log(mapIter.next().value); // [Object, "baz"]

Or iterate with for..of, like this

'use strict';

var myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

for (const entry of myMap.entries()) {
  console.log(entry);
}