JavaScript : Object-Oriented Programming

Exercises

1. Write a function that converts a hexadecimal color, for example blue (#0000FF), into its RGB representation rgb(0, 0, 255). Name your function getRGB() and test it with the following code. Hint: treat the string as an array of characters:

   > var a = getRGB("#00FF00");
   > a;
   "rgb(0, 255, 0)"
   

2. What do each of these lines print in the console?

   > parseInt(1e1);
   > parseInt('1e1');
   > parseFloat('1e1');
   > isFinite(0/10);
   > isFinite(20/0);
   > isNaN(parseInt(NaN));

3. What does this following code alert?

   var a = 1;
   
   function f() {
     function n() {
       alert(a);
     }
     var a = 2;
     n();
   }
   
   f();

4. All these examples alert "Boo!". Can you explain why?
   • Example 1:

     var f = alert;
     eval('f("Boo!")');

   • Example 2:

     var e;
     var f = alert;
     eval('e=f')('Boo!');

   • Example 3:

     (function(){ return ...