# read-last-lines-ts

> Efficiently reads the last lines of a file, written in TypeScript for intellisense

Latest version **1.2.1** (published 2021-09-02) · MIT license · 0 weekly downloads

## Install

```sh
npm install read-last-lines-ts
pnpm add read-last-lines-ts
yarn add read-last-lines-ts
bun add read-last-lines-ts
```

## Health

**Score 25/100 (F)** — status: abandoned.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.2.1 |
| Published | 2021-09-02 |
| First published | 2020-08-10 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 0 |
| Unpacked size | 14.6 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 4 |
| Author | Speykious |
| Maintainers | speykious |
| Keywords | read, last, lines, file, typescript, fast |

## Links

- npm: https://www.npmjs.com/package/read-last-lines-ts
- Repository: https://github.com/Speykious/read-last-lines-ts
- npm.io page: https://npm.io/package/read-last-lines-ts

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## Recent versions

- 1.2.1 (latest) — 2021-09-02
- 1.2.0 — 2021-09-01
- 1.1.0 — 2020-08-16
- 1.0.1 — 2020-08-10
- 1.0.0 — 2020-08-10

## README

# Read Last Lines (TypeScript)

Read the last lines of a file, written in TypeScript for intellisense, rewritten
from the current [read-last-lines](https://github.com/alexbbt/read-last-lines)
package by [Alexander Bell-Towne](https://github.com/alexbbt).

Copyright © 2020 [Speykious](https://github.com/Speykious)

***
Summary
- [Read Last Lines (TypeScript)](#read-last-lines-typescript)
	- [How to install](#how-to-install)
	- [How to use](#how-to-use)
		- [CommonJS syntax](#commonjs-syntax)
		- [ESX syntax](#esx-syntax)
	- [Miscellaneous](#miscellaneous)
***

## How to install

- If you use `npm`: `npm install read-last-lines-ts --save`
- If you use `yarn`: `yarn add read-last-lines-ts`


## How to use

`read-last-lines-ts` supports absolute and relative paths since version **1.1.0**.

**New in v1.2.0**: *literally **1000** times faster!!!*

### CommonJS syntax
To read the last 10 lines of a file in utf8 encoding:
```js
const { readLastLines, readLastLinesEnc } = require("read-last-lines-ts")

// You get a Buffer from readLastLines
const buffer = readLastLines("path/to/file", 10)
console.log(buffer.toString("utf8"))

// You can specify a buffer length (default is 4096) ─ example: 50 chars at a time!
// The bufferLength parameter is the length of the internal buffer used for reading
const buffer = readLastLines("path/to/file", 10, 50)

// Alternatively, you can use this curried function for builtin string conversion
// (PS: the optional bufferLength parameter also works here)
const lines = readLastLinesEnc("utf8")("path/to/file", 10)
console.log(lines)
```
You can choose any encoding from the `BufferEncoding` enum from `fs`.
Also, the `readLastLinesEnc` function has been curried so that it is
easier to deal with encoding: just make some variable
`const rll_utf8 = readLastLinesEnc("utf8")` and you got yourself a
nice short function for reading last lines with utf8 encoding.

### ESX syntax
Same example:
```js
import { readLastLines, readLastLinesEnc } from "read-last-lines-ts"

const buffer = readLastLines("path/to/file", 10)
console.log(buffer.toString("utf8"))

// Optional bufferLength argument
const buffer = readLastLines("path/to/file", 10, 50)

// Or:
const lines = readLastLinesEnc("utf8")("path/to/file", 10)
console.log(lines)
```
You can code in JavaScript, TypeScript, CoffeeScript, whatever is in your best interest.

## Miscellaneous
The `read-last-lines-ts` package is very often
**1000s of times faster** than the `read-last-lines` package,
as these speed tests indicate:

[![Test screenshot](resources/screenshot-test.png)](resources/screenshot-test.png)

When I looked at the code for the `read` function of the `read-last-lines` package,
there were a lot of things for which I quite didn't understand the motivation behind.

There was absolutely no use of any kind of for loop or while loop, nor any use of async/await.
Maybe it was for some kind of backwards-compatibility?

Also, why did they use a custom file system library `mz/fs` instead of the native `fs`?
Was there no `fs` back then?

They also used a *ton* of async behavior on all kinds of
places where it wasn't necessary. Maybe that was a factor for how slow it is compared
to this modern sync version.

If someone wants to explain any of these things to me, or point out a bug / problem,
or request a feature, don't hesitate to raise an issue on the [github repo](https://github.com/Speykious/read-last-lines-ts). 😁

---
_Source: https://npm.io/package/read-last-lines-ts · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._