# ms
![CI](https://github.com/vercel/ms/workflows/CI/badge.svg)
Use this package to easily convert various time formats to milliseconds.
## Examples
<!-- prettier-ignore -->
```js
ms('2 days') // 172800000
ms('1d') // 86400000
ms('10h') // 36000000
ms('2.5 hrs') // 9000000
ms('2h') // 7200000
ms('1m') // 60000
ms('5s') // 5000
ms('1y') // 31557600000
ms('100') // 100
ms('-3 days') // -259200000
ms('-1h') // -3600000
ms('-200') // -200
```
### Convert from Milliseconds
<!-- prettier-ignore -->
```js
ms(60000) // "1m"
ms(2 * 60000) // "2m"
ms(-3 * 60000) // "-3m"
ms(ms('10 hours')) // "10h"
```
### Time Format Written-Out
<!-- prettier-ignore -->
```js
ms(60000, { long: true }) // "1 minute"
ms(2 * 60000, { long: true }) // "2 minutes"
ms(-3 * 60000, { long: true }) // "-3 minutes"
ms(ms('10 hours'), { long: true }) // "10 hours"
```
## Features
- Works both in [Node.js](https://nodejs.org) and in the browser
- If a number is supplied to `ms`, a string with a unit is returned
- If a string that contains the number is supplied, it returns it as a number (e.g.: it returns `100` for `'100'`)
- If you pass a string with a number and a valid unit, the number of equivalent milliseconds is returned
## TypeScript support
As of v3.0, this package includes TypeScript definitions.
For added safety, we're using [Template Literal Types](https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html) (added in [TypeScript 4.1](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-1.html)). This ensures that you don't accidentally pass `ms` values that it can't process.
This won't require you to do anything special in most situations, but you can also import the `StringValue` type from `ms` if you need to use it.
```ts
import ms, { StringValue } from 'ms';
// Using the exported type.
function example(value: StringValue) {
ms(value);
}
// This function will only accept a string compatible with `ms`.
example('1 h');
```
In this example, we use a [Type Assertion](https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#type-assertions) to coerce a `string`.
```ts
import ms, { StringValue } from 'ms';
// Type assertion with the exported type.
function example(value: string) {
try {
// A string could be "wider" than the values accepted by `ms`, so we assert
// that our `value` is a `StringValue`.
//
// It's important to note that this can be dangerous (see below).
ms(value as StringValue);
} catch (error: Error) {
// Handle any errors from invalid vaues.
console.error(error);
}
}
// This function will accept any string, which may result in a bug.
example('any value');
```
You may also create a custom Template Literal Type.
```ts
import ms from 'ms';
type OnlyDaysAndWeeks = `${number} ${'days' | 'weeks'}`;
// Using a custom Template Literal Type.
function example(value: OnlyDaysAndWeeks) {
// The type of `value` is narrower than the values `ms` accepts, which is
// safe to use without coercion.
ms(value);
}
// This function will accept "# days" or "# weeks" only.
example('5.2 days');
```
## Related Packages
- [ms.macro](https://github.com/knpwrs/ms.macro) - Run `ms` as a macro at build-time.
## Caught a Bug?
1. [Fork](https://help.github.com/articles/fork-a-repo/) this repository to your own GitHub account and then [clone](https://help.github.com/articles/cloning-a-repository/) it to your local device
2. Link the package to the global module directory: `npm link`
3. Within the module you want to test your local development instance of ms, just link it to the dependencies: `npm link ms`. Instead of the default one from npm, Node.js will now use your clone of ms!
As always, you can run the tests using: `npm test`