Returns a Promise that is resolved when the given checkFn function returns a value other than null or undefined.
checkFn
null
undefined
The Promise is resolved with checkFn's return value.
The function is called initially, and then every time there are changes to the DOM children. Uses MutationObserver.
Optional
If given, then if no such element is present after this many milliseconds, the promise will resolve to null.
Returns a Promise that is resolved when the given
checkFnfunction returns a value other thannullorundefined.The Promise is resolved with
checkFn's return value.The function is called initially, and then every time there are changes to the DOM children. Uses MutationObserver.