dtoa.c contains two main functions: dtoa(), which converts a double to string, and strtod(), which converts a string to a double. It also contains a lot of support functions, most of which are for its own implementation of arbitrary-precision arithmetic. dtoa.c’s claim to fame is getting these conversions right, and that can only be done, … Read more
To concisely answer your question, everything beneath the LeftHandSideExpression production is a valid LeftHandSideExpression. I think the question you are really asking is: What is a valid LeftHandSideExpression and also assignable? The answer to that is anything that resolves to a Reference which is a well defined concept in the specification. In your example new … Read more
Simply put, there was no ECMAScript 4th Edition. From the 5th edition specification: Significant work was done to develop a fourth edition of ECMAScript. Although that work was not completed and not published as the fourth edition of ECMAScript, it informs continuing evolution of the language. The present fifth edition of ECMAScript (published as ECMA-262 … Read more
The JSON format is deliberately based on a subset of JavaScript object literal syntax and array literal syntax, and JavaScript objects can only have strings as keys – thus JSON keys are strings too. (OK, you can sort of use numbers as JavaScript object keys, but really they get converted to strings.) Note that the … Read more
There are several things that you can’t emulate from the ECMAScript 5 Object.create method on an ECMAScript 3 environment. As you saw, the properties argument will give you problems since in E3-based implementations there is no way to change the property attributes. The Object.defineProperty method as @Raynos mentioned, works on IE8, but partially, it can … Read more
As you already stated, the specification does not state any size limits / requirements for types besides Number. So this is definitally left to the implementation. For example, Chrome’s limit on strings seems to be hard coded at around 512mb (and less on 32bit). This puts a limit on the maximally possible allocation request in … 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
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
In ES5, you can get a reference to global object from within strict mode via indirect eval call: “use strict”; var global = (1,eval)(‘this’); Take a look at my article; particularly at this section on strict mode.
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