How do I run a JavaScript file on a website?

In a desktop browser, click the the “Console” button at the bottom of the Editor to open the console . The console will open up at the bottom of the preview panel. If you’ve selected a custom theme for your editor, the console will also use that theme.

#Creating and Uploading Files Give the file a name and file extension in the yellow text field. To create a file inside a specific directory, click the directory first, then click the “New File” button . Drag and drop individual files into the Project Root, or into directories within the project.

How to run code in CodePen

To execute JavaScript in a browser you have two options — either put it inside a script element anywhere inside an HTML document , or put it inside an external JavaScript file (with a . js extension) and then reference that file inside the HTML document using an empty script element with a src attribute.