Custom Tasks in the Palette

I want this example in the javascript not in the node js. Any one can help

What are you referring to as JavaScript as opposed to Node.js?

Yes i am using the javascript instead of node js

Do you mean client side javascript, to only run in the browser? So then you will have to bundle the app.js. The following internal command is doing this:

$ npm install && npm run build

With webpack, this will bundle the node.js application to the newly created public folder (cf. app.js file), which can be used inside the browser.

Node.js is a JavaScript runtime. Using JavaScript instead of Node.js makes no sense. Please clarify what you want to do.