Function isNumber

Checks if a value is typeof number.

Remarks

For a stricter check, see isSafeNumber and isSafeInteger.

Example

Basic usage

isNumber(0) // true
isNumber(1) // true
isNumber(2.2) // true
isNumber(NaN) // true
isNumber(Infinity) // true

isNumber('3') // false
isNumber(null) // false
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Type narrowing

const value: number | string

if (isNumber(value)) {
  value // type: number
} else {
  value // type: string
}

// or
if (!isNumber(value)) {
  value // type: string
} else {
  value // type: number
}
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Paired with assert

import { assert } from 'uft'

const paid: number | null
assert(isNumber(paid), 'missing payment')
paid // type: number
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