Simple canvas example

HTML

<canvas id="mycanvas" width="300" height="300">

CSS

canvas {
    border: 1px solid #000;
}

JavaScript

var canvas = document.getElementById('mycanvas');
var ctx = canvas.getContext('2d');
ctx.fillStyle = '#000';
ctx.fillRect(125, 125, 50, 50);<!DOCTYPE html>
<html lang="pt-br">
  <head>
    <meta charset="utf-8">
   <title>JS- funcao simples</title>

     <h1>JS - Aula 4: Funcao Simples</h1>
     <form>
       <input type=  "button"  value= "  Hello">
       <script src="hellofunction.js"></script>
       <script>  hello()   </script>
      </form>
  </body>
</html>
          function hello(){
           var nome;
          nome = prompt(" qual e o seu nome?  ");
       alert("  Hello" + nome ");


}