Workaround for .NET breaking on `clientID.startsWith`

Function.prototype.startsWith.js

// Workaround for .NET breaking on `clientID.startsWith`

// Name:        MicrosoftAjaxWebForms.debug.js
// Assembly:    System.Web.Extensions

// Line: 722
// Error: Object doesn't support this property or method

/*
function Sys$WebForms$PageRequestManager$_matchesParentIDInList
(clientID, parentIDList) {
   for (var i = 0, l = parentIDList.length; i < l; i++) {
       if (clientID.startsWith(parentIDList[i] + "_")) {
           return true;
       }
   }
   return false;
}
*/

// Workaround
Function.prototype.startsWith = function(){ return false; };

MicrosoftAjaxWebForms.debug.js

// Explaination of what's going wrong with this code
while (element) {
	if (element.id) element.id.startsWith("whatever");
	
	// when element is an Element its `id` is a string
	// when element is a Document its `id` is usually undefined
	// when a JavaScript framework sets document.id to a function,
	//     its `id` will not have the `startsWith` method
	// 
	// If they used `element.getAttribute('id')` instead, this wouldn't be a problem
	// If JavaScript frameworks did not set document.id to a function then this wouldn't be a problem
	
	element = element.parentNode;
}


// Complete original source
//     from http://www.infinitezest.com/SourceViewer/AJAXSourceMethod.aspx?Method=_getPostBackSettings(element,%20elementUniqueID)
function Sys$WebForms$PageRequestManager$_getPostBackSettings(element, elementUniqueID) {
  var originalElement = element;
  var proposedSettings = null;
  while (element) {
    if (element.id) {
      if (!proposedSettings && Array.contains(this._asyncPostBackControlClientIDs, element.id)) {
        proposedSettings = this._createPostBackSettings(true, this._scriptManagerID + '|' + elementUniqueID, originalElement);
      }
      else {
        if (!proposedSettings && Array.contains(this._postBackControlClientIDs, element.id)) {
          return this._createPostBackSettings(false, null, null);
        }
        else {
          var indexOfPanel = Array.indexOf(this._updatePanelClientIDs, element.id);
          if (indexOfPanel !== -1) {
            if (this._updatePanelHasChildrenAsTriggers[indexOfPanel]) {
              return this._createPostBackSettings(true, this._updatePanelIDs[indexOfPanel] + '|' + elementUniqueID, originalElement);
            }
            else {
              return this._createPostBackSettings(true, this._scriptManagerID + '|' + elementUniqueID, originalElement);
            }
          }
        }
      }
      if (!proposedSettings && this._matchesParentIDInList(element.id, this._asyncPostBackControlClientIDs)) {
        proposedSettings = this._createPostBackSettings(true, this._scriptManagerID + '|' + elementUniqueID, originalElement);
      }
      else {
        if (!proposedSettings && this._matchesParentIDInList(element.id, this._postBackControlClientIDs)) {
          return this._createPostBackSettings(false, null, null);
        }
      }
    }
    element = element.parentNode;
  }
  if (!proposedSettings) {
    return this._createPostBackSettings(false, null, null);
  }
  else {
    return proposedSettings;
  }
}

Hi,

I am using mootools in sharepoint 2013.
I am getting error in ie8 as "Object doesn't support this property or method". in my sharepoint master page I included as below

<script type="text/javascript" src="/sites/clientcide-mootools-2.10.js">// </script> <script type="text/javascript" src="/sites/pagefunctions.js">// </script> <script type="text/javascript" src="/sites/SuggestedSearch.js">// </script> <script type="text/javascript" src="/sites/SuggestedData.js">// </script> <script type="text/javascript" src="/sites/Navigation.js">// </script>

Not sure where it is conflicting. Please help me out with solution