Javascript is one of the most popular programming languages in the world , with a wide range of applications from browsers to servers, many companies looking to...
That means you opened dev tools for the editor, not preview. The message includes the text: "Note: this is the developer tools console for the Construct editor. If you're looking for developer tools for preview, be sure to open developer tools for the preview window instead."
Make sure the preview window is focused when you press F12.