Is there a way or a script that I can use in ARCGIS online as a geoprocessing tool that whenever a polygon is drawn on screen it is used as a lasso where the polygon can be used a selection boundary. The feature selected in the boundary will lthen need to be export, which I already know how to do. I have set up everything in the webapp builder already, just need to know how to satisfy this "task URL" scheme.
Thanks in advance.
You'll want to configure the input to your model/script as a "feature set", and then use that feature as the input to the Select Layers By Location. See this help for more information on using a feature set. It's Desktop help, but once it works in ArcMap, it'll work as a gp service.