[Sanddancer]

This isn't IEEE 754 floating point, but rather Javascript floats. For example, it gets (n!=0)/0 wrong by using the javascript NaN value instead of the IEEE 754 value of +-Infinity. For a playground like this, I think that it would be interesting to show how IEEE 754 and Javascript differ -- division by zero, the max function, etc.

Edit: I had misremembered one of the differences. Javascript does get division by zero correct. The biggest differences are in the comparisons, Javascript propagates NaNs more frequently.

[cremno]

Why do they even differ?

[Sanddancer]

Decisions made when javascript was being written. Certain functions were decided to be more non-numeric than what the floating point spec called for.