Manuals and specifications – JavaScript Tutorials

This tutorial 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.

However, because it is so structured, it might be difficult to grasp at first. So, if you’re looking for the most reliable source of language specifics, the specification is the place to go. But it’s not something you’d use every day.

A new specification version is released every year. In-between these releases, the latest specification draft is at

To read about new bleeding-edge features, including those that are “almost standard” (so-called “stage 3”), see proposals at

Also, if you’re developing for the browser, then there are other specifications covered in the second part of the tutorial.


Although, it’s often best to use an internet search instead. Just use “MDN [term]” in the query, e.g. to search for parseInt function.

Compatibility tables

JavaScript is a developing language, new features get added regularly.

To see their support among browser-based and other engines, see:

All of these sites are important in real-world development since they offer relevant information on language details, support, and so on.

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