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POJavascript library for event handling has strange 'undefined' error
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  1. POJavascript library for event handling has strange 'undefined' error
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    copied!<p>I have been working on a javascript library for event handling. Here is some of the library's code:</p> <pre><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&lt;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&lt;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| })(); </code></pre> <p>All seems fine in that...</p> <p>And then On my webpage, here is what I have to test it out:</p> <pre><code>01| &lt;div id="enter"&gt;Begin!&lt;/div&gt; 02| &lt;script&gt; 03| _("#enter").click(function(){ 04| _("#enter").print("It worked!"); 05| }) 06| &lt;/script&gt; </code></pre> <p>Seems fine here too.</p> <p>It seems like this should work, but instead I get an error that reads: <code>'undefined' is not an object (evaluating this.elem.length)[line 29 in the library]</code></p> <p>Does anyone know how I can fix this error?</p> <p>Help is greatly appreciated.</p> <p>Thank you.</p>
 

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