document.getElementByID - checking whether an element has been found or not

Question

Here's a sample code, that opens an internet explorer window, navigates to google, and gets some element on the page by its unique id:

set ie = CreateObject("InternetExplorer.Application")

ie.navigate("www.google.com")
ie.visible = true

while ie.readystate <> 4
    wscript.sleep 100
WEnd

set some_object = ie.document.getelementbyid("xjsc")

MsgBox some_object.tagname, 0

This sample brings me a DIV popup, which satisfies me completely.

But at the next step I'd like to check whether some id exists in the page, or not. Unfortunately, I can't just be, like,

set some_object = ie.document.getelementbyid("some_non_existant_id")
if some_object.tagname = "" then
...

because it gives me the following error:

ie.vbs(12, 1) Microsoft VBScript runtime error: Object required: 'some_object'

So, what's the best practice to check whether an element has been found or not?

Solution

if isObject(some_object) then 

if the variable holds an object then it was found ...

[update] After some tests and some comments, you need to use the isNothing method..

since you are setting an object it will always be an object variable type, but if it is not found it is set to nothing ..

if isNothing(some_object) then

I have checked the above with your sample code, and it works as expected..

in vbscript terms it would be

if some_object is nothing then

Comments

[Kirill Leontev]

yeah, but it retruns true for me in BOTH cases, even when nothing was found!

[Gabriele Petrioli]

@be here now, check out isNull (or even isEmpty). According to specs, it returns null if nothing is found..

[Kirill Leontev]

I did, they all seem to output false regardless the element has been found or not.

[Kirill Leontev]

Things are getting weird.... D:\work\_tmp\ie.vbs(12, 1) Microsoft VBScript runtime error: Type mismatch: 'isnothing' By the way, isNothing is a VB6 function, isn't it? I havent found it in VBScript refs.

[Gabriele Petrioli]

@be here now, you are right .. i was thinking in terms of vb.. vbscript equivalent is if some_object is nothing then