Why this is not a valid CSS selector using querySelectorAll in JS? [duplicate]

Question

I'm trying to find in my DOM all the img elements with 2x class using Vanilla JS. I'm using the querySelectorAll method like this:

document.querySelectorAll('img.2x');

But it throws this error at the console log:

Uncaught DOMException: Failed to execute 'querySelectorAll' on 'Document':
'img.2x' is not a valid selector.

Why img.2x is not a valid selector? Thanks.

Answer 1

While it certainly does look valid, you'll need to explicitly escape any digits that begin a CSS class in order to use it within your selector:

document.querySelectorAll('img.\\2x');