The word pony fill doesn't get thrown around all that much. I've only seen it where sometimes there's proposals for new things. And if they're not approved yet, it doesn't make sense. You shouldn't be throwing that on the prototype of the different JavaScript objects. The kind of role of thumb is you'd never modify the prototype unless it is something that is approved and coming to all the browsers or is in some of the browsers. So if that's the case and you know what, I just want to play with it right now just to see how it works then you you reach for a pony fill.