Funny enough my impression of JS (the kind you'd write in 2007 more than the type you see now, mind you) is that it's remarkably tolerant; many idioms and operations which would cause, in other languages, runtime errors or compile errors, would just get steamrolled over in JS because of just how much built-in flexibility the uber-weak type system (plus liberal use of the prototype pattern in the stdlib) allows for.
- Wanna subtract a string from a number? That's not a type error, that's a `NaN` -- which is just a perfectly-valid IEEE 754 float, after all, and we all float down here.
- Hell -- arithmetic between arbitrary data types? Chances are you get `[object Object]` (either as a string literal or an *actual* object), which you can still operate on.
Frankly, while I haven't had a frontend focus in about 15 years, I struggle to think of any situation where calling a stdlib function or standard language feature would result in an actual exception rather than just an off behaviour that'll accumulate over time the more of them you stack on eachother. I guess calling an undefined variable is a ReferenceError, but beyond that...
(This comment shouldn't be taken as an endorsement of this school of language design)