javascript - Why does Math.min([]) evaluate to 0?

Why does Math.min([]) evaluate to 0?

I would expect that it would evaluate to NaN since MDN's manpage for Math.min states "If at least one of the arguments cannot be converted to a number, NaN is returned."

So I guess the refined question is why does [] coerce to 0? Especially considering that [] is truthy (i.e. !![] === true) and Math.min(true) === 1. I am thinking about this wrong?

Tested on Node v7.0.0

Answer

Why does Math.min([]) evaluate to 0?

Because the spec says so:

Math.min casts each parameter to a number using...

ToNumber casts objects to a number using...

ToPrimitive casts objects to primitive values using...

[[Default Value]] internal method converts objects to primitives based on their hint parameter.

The default hint for all objects is string. Which means the array gets converted to a string, which for [] is "".

ToNumber then converts "" to 0, per the documented algorithm

Math.min then takes the only parameter and returns it, per its algorithm.