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.