JS- Compound Operators

<!DOCTYPE html>
<html>

  <head>
    <script type="text/javascript">
      var a=10,b=50;
      document.write("<br>a = " + a + ", b = " + b);
      a += 1;  //Addition Operator
      document.write("<br>a = " + a + ", b = " + b);
      b -= 10; //Substraction Operator
      document.write("<br>a = " + a + ", b = " + b);
      b *= a;  //Product Operator
      document.write("<br>a = " + a + ", b = " + b);
      b /= a;  //Division Operator
      document.write("<br>a = " + a + ", b = " + b);
      b %= a;  //Modulus Operator
      document.write("<br>a = " + a + ", b = " + b);r
    </script>
  </head>

</html>