JavaScript comments can be used to explain JavaScript code, and to make it more readable. JavaScript comments can also be used to prevent execution, when testing alternative code.

Code Editor (Try it) With our online code editor, you can edit code and view the result in your browser

JavaScript statements are composed of: Values, Operators, Expressions, Keywords, and Comments. This statement tells the browser to write "Hello Dolly." inside an HTML element with id="demo":

JavaScript Comments. Not all JavaScript statements are "executed". Code after double slashes // or between /* and */ is treated as a comment. Comments are ignored, and will not be executed:

The W3Schools online code editor allows you to edit code and view the result in your browser

Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.

HTML comments are not displayed in the browser, but they can help document your HTML source code.

The comment tag is used to insert comments in the source code. Comments are not displayed in the browsers. You can use comments to explain your code, which can help you when you edit the source code at a later date.

At W3Schools you will find complete references about HTML elements, attributes, events, color names, entities, character-sets, URL encoding, language codes, HTTP messages, browser support, and more: HTML Elements

Why Study JavaScript? JavaScript is one of the 3 languages all web developers must learn: 1. HTML to define the content of web pages. 2. CSS to specify the layout of web pages. 3. JavaScript to program the behavior of web pages