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https://github.com/sharpart555/nexline
Read file, stream, string, buffer line by line without putting them all in memory. It supports cool features like `custom line separator`, `various encodings`, `reverse mode`, `iterable protocol`
https://github.com/sharpart555/nexline
buffer encodings file line lineseparator next nodejs npm read readline reverse split stream
Last synced: 3 months ago
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Read file, stream, string, buffer line by line without putting them all in memory. It supports cool features like `custom line separator`, `various encodings`, `reverse mode`, `iterable protocol`
- Host: GitHub
- URL: https://github.com/sharpart555/nexline
- Owner: sharpart555
- License: mit
- Created: 2019-06-28T14:31:29.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2022-12-30T18:12:49.000Z (about 2 years ago)
- Last Synced: 2024-09-02T02:01:56.608Z (5 months ago)
- Topics: buffer, encodings, file, line, lineseparator, next, nodejs, npm, read, readline, reverse, split, stream
- Language: JavaScript
- Homepage: https://www.npmjs.com/package/nexline
- Size: 567 KB
- Stars: 16
- Watchers: 1
- Forks: 1
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Nexline
[](https://www.npmjs.com/package/nexline)
[](https://www.npmjs.com/package/nexline)
[](https://www.npmjs.com/package/nexline)
[](https://github.com/sharpart555/nexline/blob/master/LICENSE)
Read file, stream, string, buffer line by line without putting them all in memory.\
It supports cool features below.
* Lightweight
* Iterable protocol
* Handle large file with small memory footprint
* Support various input types (file, stream, string, buffer)
* Support various encodings
* Support reverse mode
* Support custom, multiple line separators
* Support multiple inputs
## Why I made this?
Node.js's default readline module is great but it's `pause()` method does not work immediately.\
I made wrapper to fix that issue before, but it was not enough.\
Even if `pause()` works immediately, it is still inconvenient.\
If I want to execute async function over line by line in large file, I have to call `pause()` and `resume()` at every line.\
I needed better way to do that without putting them all in memory.
## Breaking changes in 1.0.0
* `lineSeparator` default value is changed from `['\n', '\r\n']` to `'\n'` for better performance
* If you want to handle both CRLF and LF, set `lineSeparator: ['\n', '\r\n']`
* Support reverse mode.
* Support file descriptor as input
* Improve performance
* Optimize memory usage
## Install with npm
Required Node.js version >= **8.0.0**
```
npm install nexline
```
## How to use
### Use `next()` method
```js
const nexline = require('nexline');
async function main () {
const nl = nexline(...);
while(true) {
const line = await nl.next();
console.log(line);
if (line === null) break; // If all data is read, returns null
}
}
```
### Use as iterator ( Requires node >= 10 )
```js
const nexline = require('nexline');
async function main () {
const nl = nexline(...);
// nexline is iterable
for await (const line of nl) console.log(line);
}
```
### Use file as input
* Don't forget to close file descriptor after finish
* You can use `autoCloseFile: true` to close file descriptor automatically
```js
const nl = nexline({
input: fs.openSync(path_to_file, 'r'),
// autoCloseFile: true,
});
```
### Use stream as input
```js
const nl = nexline({
input: fs.createReadStream(path_to_file),
});
```
### Use string as input
```js
const nl = nexline({
input: 'foo\nbar\nbaz',
});
```
### Use buffer as input
```js
const nl = nexline({
input: Buffer.from('foo\nbar\nbaz'),
});
```
### Use multiple input
```js
const nl = nexline({
input: [
fs.openSync(path_to_file1, 'r'),
fs.createReadStream(path_to_file2),
'foo\nbar\nbaz',
Buffer.from('foo\nbar\nbaz'),
],
});
```
### Use other encodings
[See encodings supported by iconv-lite](https://github.com/ashtuchkin/iconv-lite/wiki/Supported-Encodings)
```js
const nl = nexline({
input: fs.openSync(path_to_file, 'r'),
encoding: 'cp949',
});
```
### Use other lineSeparator
```js
const nl = nexline({
input: 'foo;bar;baz',
lineSeparator: ';',
});
```
### Use multiple lineSeparator
```js
const nl = nexline({
input: 'foo\r\nbar\nbaz',
lineSeparator: ['\n', '\r\n'], // You can handle both LF and CRLF like this.
});
```
### Reverse mode
```js
const nl = nexline({
input: fs.openSync(path_to_file, 'r'), // NOTE: You cannot use stream in reverse mode.
reverse: true,
});
```
## Methods
| Name | Description |
| ------------- | --------------- |
| next() | **async**, It returns line until all data is read, after then returns `null` |
| close() | Close nexline |
## Options
| Name | Default | Description |
| ------------- | --------------------------- | --------------- |
| input | undefined | **Required.** File descriptor, stream, string, buffer, You can provide multiple inputs using array |
| lineSeparator | '\n' | Any string more than one character. You can provide multiple line separator using array |
| encoding | 'utf8' | [See encodings supported by iconv-lite](https://github.com/ashtuchkin/iconv-lite/wiki/Supported-Encodings) |
| reverse | false | Reverse mode, **Cannot use this option with stream input** because stream cannot be read from end. Use file descriptor instead |
| autoCloseFile | false | Automatically close file descriptor after all data is read |
## Contribution
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](https://github.com/sharpart555/nexline/issues/new)
## License
Copyright © 2019 Youngho Jin. Released under the [MIT License](https://github.com/sharpart555/nexline/blob/master/LICENSE)