“Object doesn’t support this action” error in IE7/IE8

Yet another IE woe – if you want your code to work on IE – be forewarned that harmless looking like the one below would break with “Object doesn’t support this action” error.

items=[];//define a array
length=items.length;//throws error since the term length is treated special in IE
for(item in items){
//again the term item is treated in a special way in IE – would throw the same error.
}

Either make sure these are local variables by prefixing them with var.

items=[];//define a array
var length=items.length;//throws error since the term length is treated special in IE
for(var item in items){
//again the term item is treated in a special – would throw the same error.
}
otherwise rename the variables
items=[];//define a array
mylength=items.length;//throws error since the term length is treated special in IE
for(myitem in items){
//again the term item is treated in a special – would throw the same error.
}

After a lot of digging, I found that any variable declared without the var keyword is considered to global in Javascript. Specifically in IE – They get attached to a global collection called document.all.

So helper methods associated with document.all such as

1. item
2. namedItem
3. tags
4. urns

and the property “length” are all considered reserved with respect to global variables in IE.

Also refrain from using these words as IDs for any HTML element.