Syntax - What does "use strict" do in JavaScript, and what is the reasoning behind it. Changes to JavaScript, Part 1: EcmaScript 5. ECMAScript 5 Strict Mode, JSON, and More. Previously I analyzed ECMAScript 5’s Object and Property system.
This is a huge new aspect of the language and deserved its special consideration. There are a number of other new features and APIs that need attention, as well. The largest of which are Strict Mode and native JSON support. ECMAScript 5 strict mode in Firefox 4. Editor’s note: This article is posted by Chris Heilmann but authored by Jeff Walden – credit where credit is due.
Developers in the Mozilla community have made major improvements to the JavaScript engine in Firefox 4. We have devoted much effort to improving performance, but we’ve also worked on new features.