`injectScript` should wait for script to load

[deaz]

Feature Request

Currently, injectScript returns immediately after appending a script. It would make sense to wait until "load" event is fired, so the caller knows that the script is injected and ready to use.

Is your feature request related to a bug?

N/A

What are the alternatives?

One alternative is to add a new option to options to enable such behavior. This way it can be opt-in and won't change current behavior.
Another way is to return script from the function and allow users to do whatever they want with the object.