<script type="text/javascript">
var Anim = function() {
  alert('nihao');
};
Anim.prototype.start = function() {
  alert('start');
};
Anim.prototype.stop = function() {
   alert('stop');
};
var myAnim = new Anim();
myAnim.start();
myAnim.stop();
</script>

<script type="text/javascript">
var Anim = function() {
  alert('nihao');
};
Anim.prototype = {
 start: function() {
  alert('start');
 },
 stop: function() {
  alert('stop');
 }
};
var myAnim = new Anim();
myAnim.start();
myAnim.stop();
</script>

<script type="text/javascript">
var Anim = function() {
  alert('nihao');
};
Function.prototype.method = function(name, fn) { // 这个很有作用
 this.prototype[name] = fn;
};
Anim.method('start', function() {
 alert('start');
});
Anim.method('stop', function() {
 alert('stop');
});
var myAnim = new Anim();
myAnim.start();
myAnim.stop();
</script>