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Since only IE5+ is affected by the memory problem, the only file that we have changed in HM4.1.1 is HM_ScriptDOM.js.
Early in the script, we initialize an empty array to store all the relevant JS variables that we will create later, and create a function that will store any variable passed to it in the array.
if(HM_IE) {
HM_a_ElementsCreated = [];
function HM_f_StoreElement(el){
HM_a_ElementsCreated[HM_a_ElementsCreated.length] = el;
}
}
In the
function HM_f_MakeElement(menuid) {
var MenuObject;
MenuObject = document.createElement("DIV");
if(HM_IE)HM_f_StoreElement(MenuObject);
...
}
In the
function HM_f_MakeItemElement(menucount) {
var ItemElement = document.createElement("DIV");
if(HM_IE)HM_f_StoreElement(ItemElement);
...
if(ItemElement.hasImage) {
var ImageElement = document.createElement("IMG");
if(HM_IE)HM_f_StoreElement(ImageElement);
...
}
...
}
At the end of our script, we place an onunload handler for IE users. If there is already an onunload handler assigned to the page, it is stored in HM_f_OtherOnUnload, in the same way that we store already assigned onload and onresize handlers.
When the user leaves the page, all JS variables that refer to elements are set to null. Then we cycle through the HM_a_ElementsCreated array, and set all properties of each element that refer to other elements to null. Finally any properties of the menu tree object are nulled.
Once this is done, any other onunload handler is executed by calling
if(HM_IE) {
HM_f_OtherOnUnload = (window.onunload) ? window.onunload : new Function;
window.onunload = function(){
HM_CurrentMenu = null;
HM_CurrentItem = null;
HM_CurrentTree.treeParent = null;
HM_CurrentTree.startChild = null;
var Eclength = HM_a_ElementsCreated.length;
for(var i=Eclength-1; i>=0; i--){
TempElement = HM_a_ElementsCreated[i];
TempElement.parentMenu = null;
TempElement.parentItem = null;
TempElement.itemElement = null;
TempElement.currentItem = null;
TempElement.child = null;
TempElement.siblingBelow = null;
TempElement.imgLyr = null;
}
TempElement = null;
for(var i=0; i<HM_TotalTrees; i++) {
HM_a_TopMenus[i].tree.startChild = null;
HM_a_TopMenus[i].tree.treeParent = null;
}
HM_f_OtherOnUnload();
}
}
You will need to overwrite previous versions of the above file to upgrade to 4.1.1.
On the next page, the sample page included in the download.
Produced by Peter Belesis and
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All Rights Reserved. Legal Notices.
Created: October 2, 2001
Revised: October 2, 2001
URL: http://www.webreference.com/dhtml/column59/3.html
