1

I have been working on a javascript library for event handling. Here is some of the library's code:

01| (function(){
02|     var int,
03|         Jist = function(s){
04|             return new Jist.fn.init(s);
05|         };
06|     Jist.fn = Jist.prototype ={
07|         init : function(s){
08|             if(!s){
09|                 return this;
10|             }
11|             else{
12|                 this.length = 1;
13|                 if (typeof s === "object"){
14|                     this[0] = s;
15|                 }
16|                 else if(typeof s === "string"){
17|                     var obj;
18|                     obj = document.querySelectorAll(s);
19|                     this[0] = obj;
20|                     this.elem = this[0];
21|                 }
22|                 return this;
23|             }
24|         },
25|     };
26|     Jist.fx ={
27|         event : function(event,callback,state){
28|             var dummy = (state) ? false : state; 
29|             for(var i=0; i<this.elem.length; i++) {
30|                 this.elem[i].addEventListener(event,callback,dummy);
31|             }
32|             return this;
33|             },
34|     }
35|     Jist.fn.init.prototype = Jist.fn;
36|     Jist.fn.init.prototype = {
37|         print : function(txt){
38|             for(var i=0; i<this.elem.length; i++) {
39|                 this.elem[i].innerHTML = txt;
40|             }
41|             return this;
42|         },
43|         click : function(callback){
44|             Jist.fx.event("click",callback);
45|             return this;
46|         },
47|     };
48|     window.Jist = window._ = Jist;
49| })();

All seems fine in that...

And then On my webpage, here is what I have to test it out:

01| <div id="enter">Begin!</div>
02| <script>
03|    _("#enter").click(function(){
04|       _("#enter").print("It worked!");
05|    })
06| </script>

Seems fine here too.

It seems like this should work, but instead I get an error that reads: 'undefined' is not an object (evaluating this.elem.length)[line 29 in the library]

Does anyone know how I can fix this error?

Help is greatly appreciated.

Thank you.

4

1 回答 1

1

您是否尝试过打印“this”的值?您确定在正确的范围内执行吗?

于 2013-11-07T04:06:57.383 回答