local-iso-dt/README.md

Convert the most common types of dates into ISO8601/RFC3339-formatted YYYY-MM-DDTHH:MM:SS strings in the local timezone

# local-ISO-dt — toISOString() in the local timezone

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Convert the most common types of dates and timestamps into datetime strings in the standard `YYYY-MM-DDTHH:MM:SS` format, in the *local* timezone. This format is called [ISO8601 or RFC3339, the difference](https://stackoverflow.com/questions/522251/whats-the-difference-between-iso-8601-and-rfc-3339-date-formats/522281#522281) being that RFC3339 mandates a four-digit year and allows the 'T' to be replaced with a space. The library outputs the 'T' between the date and the time, which you can easily `.replace('T', ' ')`.

The YYYY-MM-DD date format is great because sorting alphabetically is equivalent to sorting chronologically. Other date formats, in particular the idiosyncratic `m/dd/yy` American format, do not have this property.


# Features

Supports and automatically detects the parameter being a:

* number of seconds/milliseconds/microseconds/nanoseconds since epoch
* [Date](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) object
* `YYYY-MM-DD[THH:MM:SS]` string
* falsy value - the current date will be returned


# Install

```sh
npm i local-iso-dt
```


# Usage

* TypeScript: `import { localISOdt } from 'local-iso-dt';`
* ES modules `.mjs` files: `import { localISOdt } from 'local-iso-dt/index.mjs';`
* Old school CommonJS:  `const { localISOdt } = require('local-iso-dt/index.js');`

This is a [hybrid npm package](https://2ality.com/2019/10/hybrid-npm-packages.html) (created using variation 2.4.1 described on that page), with [conditional exports](https://nodejs.org/api/esm.html#esm_conditional_exports) that enable named imports even from TypeScript code generating ES Modules, which would otherwise [only](https://github.com/apollographql/apollo-server/issues/1356#issuecomment-681313954) support [default (not named) imports from the CommonJS](https://stackoverflow.com/questions/61549406/how-to-include-commonjs-module-in-es6-module-node-app) target of this package ([TypeScript doesn't support .mjs input files](https://github.com/microsoft/TypeScript/issues/27957)).


# Examples

```js
import { localISOdt } from 'local-iso-dt';  // or...
// const { localISOdt } = require('local-iso-dt/index.js');

// Prefix log messages with the current date in the
// local timezone in YYYY-MM-DDTHH:MM:SS format
console.log(localISOdt(), 'Starting job...');

// 2017-07-15T05:57:36 if you're in the Pacific (-0700) timezone
localISOdt(1500123456);
```


# Author

[Dan Dascalescu](https://dandascalescu.com)


# License

MIT