PHP implements jQuery extension functions

It's the contains function, which the book says filters the selected set of elements by their contents, and I kept reporting errors when I was running the code, and I wrote it myself because it wasn't in the library.
The code is as follows:

 
function yhCheckIsIncludingValue(element , pattern) 
{ 
var bool = false; 
var childrenNodes = element.childNodes; 
if (childrenNodes.length == 0) 
{ 
if (element.nodeValue != null) 
{ 
if (pattern.exec(element.nodeValue) != null) 
{ 
return true; 
} 
} 
} 
if (childrenNodes.length != 0) 
{ 
for (var i = 0 ; i < childrenNodes.length ; i++) 
{ 
if (bool = yhCheckIsIncludingValue(childrenNodes , pattern)) break; 
} 
} 
return bool; 
} 
//Apply this function to the chain of functions
$.fn.contains = function(text) 
{ 
var text = $.trim(text); 
if (text == 'undefined') return this; 
var pattern = new RegExp(text , 'i'); 
return this.filter(function(){ 
return yhCheckIsIncludingValue(this , pattern); 
}); 
} 

Internet explorer works fine. What happens to other browsers?