A Quick JavaScript Test on Scope and Closure

I found this article on how scope works in JavaScript at DailyJS.
JS101: A Brief Lesson on Scope

There is a code snippet that demonstrates a possibly confusing behavior of closure and scoping for beginners. Here is the code:

function example() {
    var o = {}, i = 0;
    for (i = 0; i < 3; i++) {
        o[i] = function() { console.log(i); };
    }
    o[0]();
    o[1]();
    o[2]();
}

example();

This returns the following in console:

3
3
3

So I was thinking, next time I interview someone for hire, I might show this snippet and ask him/her to make it return 0, 1, 2 instead.

If you read the comments in the original post, you can find two solutions.

About

Hidenari Nozaki: Software Engineer
Follow @ghiden

Published

Tags

• javascript 10