Run JavaScript Code Online

Execute JavaScript code right in your browser and see the results. Save, share, and collaborate on your JavaScript code online. Detect and fix JavaScript errors with built-in syntax highlighter and validator. Learn JavaScript programming with an extensive and hand-picked database of JavaScript code examples. No browser plugins or additional desktop software are needed for using the Online JavaScript code runner. It's free.
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Run JavaScript Code Online

Run JavaScript code online using ReqBin online interpreter. The online ReqBin JavaScript executor supports core JavaScript methods and libraries. For security reasons, some JavaScript methods are not supported.

  • Write & test JavaScript code online
  • Execute JavaScript code directly in your browser
  • Share and discuss your JavaScript code snippets online
  • Built-in JavaScript code syntax highlighter and validator

What is JavaScript?

JavaScript is a high-level programming language that allows you to execute complex scenarios on web pages, such as making requests to third-party API services, dynamically creating content on a page, displaying interactive maps, animating 2D/3D graphics and games, and playing music right in the browser.

Almost all modern browsers support JavaScript, and the main competition between them is to improve JavaScript execution runtime and reduce memory consumption. Google's V8 JavaScript engine does these tasks better than others, and Microsoft recently ditched its JavaScript engine in Edge browser in favor of V8. One of the advantages of JavaScript is that you can write and execute simple JavaScript code right in the console of your web browser by simply pressing F12; no third-party applications are required to run JavaScript code.

JavaScript code can be embedded directly into HTML in the <script> tag, or linked to an HTML page from an external URL.

JavaScript Code Example
<html>
   <head>
       <title>JavaScript Code Example</title>
       <script src="app.js"></script>
   </head>
   <body>
      <h1 id='title'>Title</h1>
      <script>
         document.getElementById('title').innerHTML = "My Title";
       </script>
   </body>
</html>

JavaScript is an asynchronous and single-threaded programming language and supports event-driven, functional, and imperative programming styles. JavaScript has built-in methods for working with text, numbers, regular expressions, dates, and the browser's document object model, and is ECMAScript compliant.

Along with writing interactive web pages, JavaScript is often used to write back-ends for web servers (thanks to Node.js), allowing developers to have almost the same technology stack for both the UI and server-side development.

What are the advantages of JavaScript?

  • JavaScript is fast and works in the user's browser.
  • JavaScript is easier to learn compared to other popular languages like C ++.
  • JavaScript is cross-platform; your code will work equally well in browsers on Windows macOS and Linux.
  • JavaScript is extremely popular, and you can quickly find any answers to your JavaScript questions.
  • JavaScript is client-side, and a well-designed JavaScript application can significantly reduce the load on your web server by performing some of the computation directly in the browser.

How to run JavaScript code online?

With the ReqBin Online JavaScript code runner, you can run JavaScript code-snippets directly on this web page. No desktop apps or browser plugins are required. Just enter the JavaScript code and click "Execute". Built-in JavaScript syntax highlighting will highlight JavaScript syntax and errors as you type JavaScript code.

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