<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title> JavaScript DOM getElementbyId Method </title> </head> <body> <h2>Square Number</h2> <script> function getsquare(){ var number=document.getElementById("number").value; alert("Square of " + number + " is " + number*number); } </script> <form> Enter No : <input type="text" id="number" name="number"/> <input type="button" value="Square" onclick="getsquare()"/> </form> </body> </html>
