---
title: validateNumber
tags: math,intermediate
---

Checks if the given value is a number.

- Use `parseFloat()` to try to convert `n` to a number.
- Use `!Number.isNaN()` 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.

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

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