For you, without using a browser that supports strict mode: A Use Strict Directive is an ExpressionStatement in a Directive Prologue whose StringLiteral is either the exact character sequences “use strict” or ‘use strict’. A Use Strict Directive may not contain an EscapeSequence or LineContinuation.
Currently, I’ve modified a version of the EcmaScript.NET inside my YUICompressor.NET port (project). If you grab the source code from here, I’ve included my modified code in the project, which you can reference. This is the only source of code i’ve found in .NET which can handle parsing javascript, server side. Unfortunately, I can’t remember … Read more
“use strict” applies only to function or program scope. So if you have fileA.js with “use strict” at the top, fileA.js executes in strict mode, and all functions defined in it will do the same when called. But fileB.js is a separate program, so the “use strict” from fileA.js doesn’t apply to it — and … Read more
It is defined in ECMAScript 3rd edition. It is available in IE 5.5+ and all in-use versions of Firefox, Chrome, Opera and Safari. You can use it safe in the knowledge that it will work. You should err on the side of caution when using it to check event support. All implementations except older Firefox … Read more
Brendan Eich wanted to do a Scheme-like language for Netscape, but reality intervened and he ended up having to make do with something that looked vaguely like C and Java for “normal” people, but which worked like a functional language. Personally I think it’s an unnecessary stretch to call ECMAScript “Lisp”, but to each his … Read more
No, you can’t disable strict mode per function. It’s important to understand that strict mode works lexically; meaning — it affects function declaration, not execution. Any function declared within strict code becomes a strict function itself. But not any function called from within strict code is necessarily strict: (function(sloppy) { “use strict”; function strict() { … Read more
The fact that this inside a function called in the global context will not point to the global object can be used to detect strict mode: var isStrict = (function() { return !this; })(); Demo: > echo ‘”use strict”; var isStrict = (function() { return !this; })(); console.log(isStrict);’ | node true > echo ‘var isStrict … Read more
It’s not like there is an official JavaScript release. All the browsers have made their own JavaScript engine – some are using the same though. But especially Internet Explorer has its own version that doesn’t support a lot of what the other browsers support, making it very difficult to make a general JavaScript reference. Edit: … Read more
Infinity and NaN aren’t keywords or anything special, they are just properties on the global object (as is undefined) and as such can be changed. It’s for that reason JSON doesn’t include them in the spec — in essence any true JSON string should have the same result in EcmaScript if you do eval(jsonString) or … Read more
Early versions of JavaScript did not allow named function expressions, and because of that we could not make a recursive function expression: // This snippet will work: function factorial(n) { return (!(n>1))? 1 : factorial(n-1)*n; } [1,2,3,4,5].map(factorial); // But this snippet will not: [1,2,3,4,5].map(function(n) { return (!(n>1))? 1 : /* what goes here? */ (n-1)*n; … Read more