To try out the Closure Compiler application with a simple JavaScript program, follow the Download the Closure Compiler compiler.jar file and save it in closure-compiler . Run the following command from the closure-compiler directory:. Summary. The download() function is used to trigger a file download from JavaScript. It specifies the contents and name of a new file placed in the browser's  Here are a few tips to make your JavaScript work in WordPress. To "load" the JavaScript file into your site, in the head, add something like this: tag in the element of your page: