The JavaScript Interview Handbook: 100+ Interview Questions/

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Solution Review: Closure, `setTimeout`, IIFE

Solution Review: Closure, `setTimeout`, IIFE

In this lesson, we will discuss the solution to the quiz in the previous lesson.

We'll cover the following...

Question: Solution review #

Explanation #

You were asked to choose the codes that will give the correct output for the following code:

Javascript (babel-node)
const array = [5, 11, 18, 25];
for (var i = 0; i < array.length; i++) {
  setTimeout(function() {
    console.log('Element: ' + array[i] + ', at index: ' + i);
    }, 3000);
}

Let’s start by going through each option one-by-one.

Option A: Correct.

Run the code below:

Javascript (babel-node)
const array = [5, 11, 18, 25];
for (let i = 0; i < array.length; i++) {
  setTimeout(function() {
    console.log('Element: ' + array[i] + ', at index: ' + i);
    }, 3000);
}

As you can see, it gives the correct answer. The only modification you need to make is declaring the iterator i using the keyword let rather than var. This fix makes use of ES6. Changing var to let changes the implementation so that the value of i ...