js get input from user

// how to take input in javascript from user
Copyvar name = window.prompt("Enter your name: ");
alert("Your name is " + name);

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

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

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

var answer = prompt("How are you? ");

Copyvar name = window.prompt("Enter your name: ");
alert("Your name is " + name);