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

chrome javascript strict mode / javascript / syntax / jslint / use-strict

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

Mark Rogers

Answer #1

The strict mode of ECMAScript 5 is a restricted subset of the JavaScript language, which eliminates relevant deficits of the language and features more stringent error checking and higher security. The following lists the differences between strict mode and normal mode (of which the first three are particularly important):

var hasStrictMode = (function() { "use strict"; return this===undefined }());