This book is a tutorial. It aims to help you gradually learn the language. But once you're familiar with the basics, you'll need other sources.
The ECMA-262 specification contains the most in-depth, detailed and formalized information about JavaScript. It defines the language.
But being that formalized, it's difficult to understand at first. So if you need the most trustworthy source of information about the language details, it's the right place. But it's not for everyday use.
The latest draft is at https://tc39.es/ecma262/.
To read about bleeding-edge features, that are not yet widely supported, see proposals at https://github.com/tc39/proposals.
Also, if you're in developing for the browser, then there are other specs covered in the second part of the tutorial.
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MDN (Mozilla) JavaScript Reference is a manual with examples and other information. It's great to get in-depth information about individual language functions, methods etc.
One can find it at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference.
Although, it's often best to use an internet search instead. Just use "MDN [term]" in the query, e.g. https://google.com/search?q=MDN+parseInt to search for
parseIntfunction. -
MSDN – Microsoft manual with a lot of information, including JavaScript (often referrerd to as JScript). If one needs something specific to Internet Explorer, better go there: http://msdn.microsoft.com/.
Also, we can use an internet search with phrases such as "RegExp MSDN" or "RegExp MSDN jscript".
JavaScript is a developing language, new features get added regularly.
To see their support among browser-based and other engines, see:
- http://caniuse.com - per-feature tables of support, e.g. to see which engines support modern cryptography functions: http://caniuse.com/#feat=cryptography.
- https://kangax.github.io/compat-table - a table with language features and engines that support those or don't support.
All these resources are useful in real-life development, as they contain valuable information about language details, their support etc.
Please remember them (or this page) for the cases when you need in-depth information about a particular feature.