What does “use strict” do in JavaScript, and what is the reasoning behind it?

Question

Recently, I ran some of my JavaScript code through Crockford\'s JSLint, and it gave the following error:

Problem at line 1 character 1: Missing \"use

Answer 1

Including use strict in the beginning of your all sensitive JavaScript files from this point is a small way to be a better JavaScript programmer and avoid random variables becoming global and things change silently.