How do I check if a number evaluates to infinity?

Question

I have a series of Javascript calculations that (only under IE) show Infinity depending on user choices.

How does one stop the word Infinity appearing a

Answer 1

A simple n === n+1 or n === n/0 works:

function isInfinite(n) {
  return n === n/0;
}

Be aware that the native isFinite() coerces inputs to numbers. isFinite([]) and isFinite(null) are both true for example.