[Javascript] Iterate Over Items with JavaScript's for-of Loop

In this lesson we will understand the For Of loop in Javascript which was introduced in ES6. The for-of loop lets you iterate of an itterable object (array, string, set, or map) and returns each objects value in a specified variable. This excludes plain objects as we will see in the lesson.

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

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

let iterable = [3, 5, 7];

iterable.foo = 'hello';

for (let i in iterable) {

  console.log(i); // 0, 1, 2, "foo", "arrCustom", "objCustom"

}

for (let i in iterable) {

  if (iterable.hasOwnProperty(i)) {

    console.log(i); // 0, 1, 2, "foo"

  }

}

for (let i of iterable) {

  console.log(i); // 3, 5, 7

}

"accCustom" and "objCustom" are not logged in second loop is because they are inherited. Not array and object's own prop.