display js functionin html code example

Example 1: print things js

console.log("Hello World");

Example 2: js outputting data

Javascript: Outputting Data
alert()
Output data in an alert box in the browser window
confirm()
Opens up a yes/no dialog and returns true/false depending on user click
console.log()
Writes information to the browser console, good for debugging purposes
WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 5
document.write()
Write directly to the HTML document
prompt()
Creates an dialogue for user input