Modern JavaScript Tutorial: simple, but detailed explanations with examples and tasks, including: closures, document and events, object oriented programming and more.
JavaScript (or "JS") is a programming language used most often for dynamic client-side scripts on webpages, but it is also often used on the server-side, using a runtime such as Node.js.
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The JavaScript Guide shows you how to use JavaScript and gives an overview of the language. If you need exhaustive information about a language feature, have a look at the JavaScript reference.