For example, if I do this:
var q = document.querySelectorAll;
q(\'body\');
I get an \"Illegal invocation\" error in Chrome. I can\'t thin
It's because you've lost the "context" of the function.
When you call:
document.querySelectorAll()
the context of the function is document
, and will be accessible as this
by the implementation of that method.
When you just call q
there's no longer a context - it's the "global" window
object instead.
The implementation of querySelectorAll
tries to use this
but it's no longer a DOM element, it's a Window
object. The implementation tries to call some method of a DOM element that doesn't exist on a Window
object and the interpreter unsurprisingly calls foul.
To resolve this, use .bind
in newer versions of Javascript:
var q = document.querySelectorAll.bind(document);
which will ensure that all subsequent invocations of q
have the right context. If you haven't got .bind
, use this:
function q() {
return document.querySelectorAll.apply(document, arguments);
}
One more concise solution:
const q=s=>document.querySelectorAll(s);
q('body');
you can use like this :
let qsa = document.querySelectorAll;
qsa.apply(document,['body']);
In my case Illegal invocation occurred due to passing undeclared variable to function as argument. Make sure to declare variable before passing to function.