created by Brian LeRoux & Andrew Lunny. sparodically uncurated by David Trejo.

isFinite function of JavaScript tests whether a number is finite.

    isFinite(42); // true
    isFinite(1/0); // false
    isFinite(0/0); // NaN is not finite -> false
    isFinite('42'); // true
    isFinite('hi'); // false

These are normal results.

    isFinite(); // false
    isFinite(undefined); // false

Undefined values are not finite. These are normal results too.

    isFinite(null); // true

Wait, what? Is null a number? It is converted into 0? Why?

Since null != 0 and null == undefined, (even thought null !== undefined) I expected null will behave something like undefined!

— @123jimin

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