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JavaScript (JS) é uma linguagem de programação compilada JIT ou interpretada simples com funções de primeira classe. Embora seja mais conhecida coma a linguagem de scripting para as páginas da Web, muitos ambientes de não navegador (inglês) também o utilizam, tais como Node.js, Apache CouchDB e Adobe Acrobat. JavaScript é uma linguagem dinâmica, Programação baseada em protótipo, multiparadigma, suporta programação orientada a objetos, imperativa, e estilos declarativos (por exemplo, programação funcional). Leia mais sobre o JavaScript.

Essa seção do site é dedicada à própria linguagem JavaScript, e não as partes que são específicas das páginas da Web ou outros ambientes de hospedagem. Para informação sobre APIs específicas das páginas da Web, por favor, consulte APIs da Web e DOM.

The standard for JavaScript is ECMAScript. As of 2012, all modern browsers fully support ECMAScript 5.1. Older browsers support at least ECMAScript 3. On June 17, 2015, ECMA International published the sixth major version of ECMAScript, which is officially called ECMAScript 2015, and was initially referred to as ECMAScript 6 or ES6. Since then, ECMAScript standards are on yearly release cycles. This documentation refers to the latest draft version, which is currently ECMAScript 2018.

Do not confuse JavaScript with the Java (linguagem de programação). Both "Java" and "JavaScript" are trademarks or registered trademarks of Oracle in the U.S. and other countries. However, the two programming languages have very different syntax, semantics, and uses.


Learn how to program in JavaScript with guides and tutorials.

Para principiantes

Head over to our Learning Area JavaScript topic if you want to learn JavaScript but have no previous experience of JavaScript or programming. The complete modules available there are as follows:

JavaScript first steps
Answers some fundamental questions such as "what is JavaScript?", "what does it look like?", and "what can it do?", along with discussing key JavaScript features such as variables, strings, numbers, and arrays.
JavaScript building blocks
Continues our coverage of JavaScript's key fundamental features, turning our attention to commonly-encountered types of code block such as conditional statements, loops, functions, and events.

Guia de JavaScript

Guia de JavaScript
A much more detailed guide to the JavaScript language, aimed at those with previous programming experience either in JavaScript or another language.


Introducing JavaScript objects
The object-oriented nature of JavaScript is important to understand if you want to go further with your knowledge of the language and write more efficient code, therefore we've provided this module to help you.
Client-side web APIs
When writing client-side JavaScript for web sites or applications, you won't go very far before you start to use APIs — interfaces for manipulating different aspects of the browser and operating system the site is running on, or even data from other web sites or services. In this module we will explore what APIs are, and how to use some of the most common APIs you'll come across often in your development work.
A re-introduction to JavaScript
An overview for those who think they know about JavaScript.
JavaScript data structures
Overview of available data structures in JavaScript.
Equality comparisons and sameness
JavaScript provides three different value-comparison operations: strict equality using ===, loose equality using ==, and the method.


Inheritance and the prototype chain
Explanation of the widely misunderstood and under-estimated prototype-based inheritance.
Strict mode
Strict mode defines that you can not use any variable before initializing it. It is a restricted variant of ECMAScript 5, for faster performance and easier debugging.
JavaScript typed arrays
JavaScript typed arrays provide a mechanism for accessing raw binary data.
Memory Management
Memory life cycle and garbage collection in JavaScript.
Concurrency model and Event Loop
JavaScript has a concurrency model based on an "event loop".
Introduction to using XPath in JavaScript
This document describes the interface for using XPath in JavaScript internally, in extensions, and from websites.


Browse the complete JavaScript reference documentation.

Standard objects
Get to know standard built-in objects Array, Boolean, Date, Error, Function, JSON, Math, Number, Object, RegExp, String, Map, Set, WeakMap, WeakSet, and others.
Expressions and operators
Learn more about the behavior of JavaScript's operators instanceof, typeof, new, this, the operator precedence, and more.
Statements and declarations
Learn how do-while, for-in, for-of, try-catch, let, var, const, if-else, switch, and more JavaScript statements and keywords work.
Learn how to work with JavaScript's functions to develop your applications.

Ferramentas e recursos

Helpful tools for writing and debugging your JavaScript code.

Firefox Developer Tools
Scratchpad, Web Console, JavaScript Profiler, Debugger, and more.
JavaScript Shells
A JavaScript shell allows you to quickly test snippets of JavaScript code.
Collaboration made easy. By adding TogetherJS to your site, your users can help each other out on a website in real time!
Stack Overflow
Stack Overflow questions tagged with "JavaScript".
JavaScript versions and release notes
Browse JavaScript's feature history and implementation status.
Edit JavaScript, CSS, HTML and get live results. Use external resources and collaborate with your team online.
JavaScript templates
This page provides a list of JavaScript template systems.
Plunker is an online community for creating, collaborating on and sharing your web development ideas. Edit your JavaScript, CSS, HTML files and get live results and file structure.

Join the JavaScript community

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