waitForFunction(pageFunction, arg[, options])

Returns when the pageFunction returns a truthy value.

Parameter	Type	Default	Description
pageFunction	function		Function to be evaluated in the page context.
arg	string	`''`	Optional argument to pass to `pageFunction`
options	object	`null`
options.polling	number or `raf`	`raf`	If `polling` is `'raf'`, then `pageFunction` is constantly executed in `requestAnimationFrame` callback. If `polling` is a number, then it is treated as an interval in milliseconds at which the function would be executed.
options.timeout	number	`30000`	Maximum time in milliseconds. Pass `0` to disable the timeout. Default is overridden by the `setDefaultTimeout` option on BrowserContext or Page.