how to take input from user javscript code example

Example 1: how to take input in javascript in coding

In JavaScript, we can get user input like this: 
var name = window.prompt("Enter your name: "); 
alert("Your name is " + name);

Example 2: javascript prompt

var person = prompt("Please enter your name", "Harry Potter");

if (person != null) {
  document.getElementById("demo").innerHTML =
  "Hello " + person + "! How are you today?";
}