JavaScript的Hook

<!DOCTYPE html>
<html>
<head>
<title>hook</title>
<meta name="generator" content="editplus" />
<meta name="author" content="" />
<meta name="keywords" content="" />
<meta name="description" content="" />
<meta http-equiv='content-type' content='text/html; charset=utf-8' />
</head>

<body>
  

<input type='button' value='fuck' onclick='fuck()' />
<input type='button' value='hook' onclick='hook()' id='hookBtn' />


<script type='text/javascript'>   1:  
   2:     
   3: function fuck() {
   4:     alert('hook');
   5: }
   6:  
   7: var isHook = false;
   8: var isReset = false;
   9:  
  10: function getEl(id) {
  11:     return typeof id === 'string' ? document.getElementById(id) : null;
  12: }
  13:  
  14: function hook() {
  15:     
  16:     if (isHook)    {        
  17:         isReset = true;    
  18:         getEl('hookBtn').value = 'hook';
  19:     } else {
  20:         fuck = function(fn) {
  21:             return function() {
  22:                 if (isReset) {
  23:                     isReset = false;
  24:                     fuck = fn;
  25:                     fn.apply(fn, arguments);
  26:                     return ;
  27:                 }
  28:  
  29:                 alert('hook it~');
  30:                 fn.apply(fn, arguments);
  31:  
  32:                 return fn;
  33:             }
  34:         }(fuck);
  35:  
  36:         getEl('hookBtn').value = 'unHook';
  37:     }
  38:  
  39:     isHook = !isHook;
  40: }
  41:  
</script>

</body>
</html>