for of vs for in javascript code example

Example 1: for of vs for in javascript

let list = [4, 5, 6];

for (let i in list) {
   console.log(i); // "0", "1", "2",
}

for (let i of list) {
   console.log(i); // "4", "5", "6"
}

// EXAMPLE 2
let pets = new Set(["Cat", "Dog", "Hamster"]);
pets["species"] = "mammals";

for (let pet in pets) {
   console.log(pet); // "species"
}

for (let pet of pets) {
    console.log(pet); // "Cat", "Dog", "Hamster"
}

Example 2: Flutter For In loop explained

void main() {
  List subjects = ['Math', 'Biology', 'Economic', 'History', 'Science'];
  for (String sName in subjects) {
    print(sName);
  }
}

Example 3: for in and for of in js

Object.prototype.objCustom = function () {}; 
Array.prototype.arrCustom = function () {};

let iterable = [3, 5, 7];
iterable.foo = "hello";

for (let i in iterable) {
  console.log(i); // logs 0, 1, 2, "foo", "arrCustom", "objCustom"
}

for (let i of iterable) {
  console.log(i); // logs 3, 5, 7
}

Example 4: for of vs for in

for (variable in enumerable) {
	// do stuff
}

Example 5: for of vs for in

const array = ['a', 'b', 'c', 'd'];

for (const index in array) {
	console.log(array[index])
}

// Result: a, b, c, d