Why can't I use "document.getElementById" in catalog item's client script

[Allen17]

error log: TypeError: Cannot read property 'getElementById' of null，I didn't check the Isolate script

[Ankur Bawiskar]

Hi Allen,

getElementById is blocked by ServiceNow since it may affect or break your functionality whenever upgrade happens or patch is applied.

but if you still want to use that then isolate script checkbox set it to false

Mark Correct if this solves your issue and also mark Helpful if you find my response worthy based on the impact.
Thanks
Ankur

[Allen17]

I have been set it false, but it still not working

[Harish KM]

Hi in Madrid we cant use DOM. If you want to access DOM you need to make isolate check box to true

[asifnoor]

Hi,

Refer to this article which suggests why you cannot use the docuemtn.getElementByID

https://hi.service-now.com/kb_view.do?sysparm_article=KB0719250