Are you a Number?

Number.isNaN() and isNaN() behave differently.

	Number.isNaN()	isNaN()
`'asdf'`	false	true
`undefined`	false	true
`'10f'`	false	true
`{}`	false	true
`"NaN"`	false	true

The MDN docs explain their differences as isNaN() coerces the parameter to a number.

Note that TypeScript only accepts unknown as the parameter type, even though JS handles additional cases (i.e. undefined).

Cases with the same behaviour:

	Number.isNaN()	isNaN()
`123`	false	false
`'123'`	false	false
`''`	false	false
`' '`	false	false
`null`	false	false
`[]`	false	false
`Infinity`	false	false
`false`	false	false
`0/0`	true	true
`NaN`	true	true

Further Reading

[Number.isNaN() - JavaScript

MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN#)

[isNaN() - JavaScript

MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN)