How to check if value is NaN in Typescript? [duplicate]

Question

Same as JavaScript, isNaN.

if (isNaN(someObject.someValue)) ...

Or the more modern Number.isNaN.

if (Number.isNaN(someObject.someValue)) ...

The difference between the two is that isNaN() will coerce the tested value into a number before checking (values with typeof value !== 'number' will return true), while Number.isNaN() won’t.

In other words, with these values, you get these results:

value	`isNaN()`	`Number.isNaN()`	`typeof value === 'number'`
`123`	`false`	`false`	`true`
`NaN`	`true`	`true`	`true`
`true`/`false`	`true`	`false`	`false`
`'a string'`	`true`	`false`	`false`
`new Date()`	`true`	`false`	`false`
`[]`	`true`	`false`	`false`
`{}`	`true`	`false`	`false`
…	`true`	`false`	`false`

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