# Validate number

JavaScript, Math · Oct 22, 2020

Checks if the given value is a number.

- Use
`parseFloat()`

to try to convert`n`

to a number. - Use
`Number.isNaN()`

and logical not (`!`

) operator to check if`num`

is a number. - Use
`Number.isFinite()`

to check if`num`

is finite. - Use
`Number`

and the loose equality operator (`==`

) to check if the coercion holds.

```
const validateNumber = n => {
const num = parseFloat(n);
return !Number.isNaN(num) && Number.isFinite(num) && Number(n) == n;
}
```

```
validateNumber('10'); // true
validateNumber('a'); // false
```