ok
Direktori : /opt/alt/alt-nodejs11/root/lib/node_modules/npm/node_modules/minipass/ |
Current File : //opt/alt/alt-nodejs11/root/lib/node_modules/npm/node_modules/minipass/README.md |
# minipass A _very_ minimal implementation of a [PassThrough stream](https://nodejs.org/api/stream.html#stream_class_stream_passthrough) [It's very fast](https://docs.google.com/spreadsheets/d/1oObKSrVwLX_7Ut4Z6g3fZW-AX1j1-k6w-cDsrkaSbHM/edit#gid=0) for objects, strings, and buffers. Supports pipe()ing (including multi-pipe() and backpressure transmission), buffering data until either a `data` event handler or `pipe()` is added (so you don't lose the first chunk), and most other cases where PassThrough is a good idea. There is a `read()` method, but it's much more efficient to consume data from this stream via `'data'` events or by calling `pipe()` into some other stream. Calling `read()` requires the buffer to be flattened in some cases, which requires copying memory. There is also no `unpipe()` method. Once you start piping, there is no stopping it! If you set `objectMode: true` in the options, then whatever is written will be emitted. Otherwise, it'll do a minimal amount of Buffer copying to ensure proper Streams semantics when `read(n)` is called. This is not a `through` or `through2` stream. It doesn't transform the data, it just passes it right through. If you want to transform the data, extend the class, and override the `write()` method. Once you're done transforming the data however you want, call `super.write()` with the transform output. For an example of a stream that extends MiniPass to provide transform capabilities, check out [minizlib](http://npm.im/minizlib). ## USAGE ```js const MiniPass = require('minipass') const mp = new MiniPass(options) // optional: { encoding } mp.write('foo') mp.pipe(someOtherStream) mp.end('bar') ``` ### collecting ```js mp.collect().then(all => { // all is an array of all the data emitted // encoding is supported in this case, so // so the result will be a collection of strings if // an encoding is specified, or buffers/objects if not. // // In an async function, you may do // const data = await stream.collect() }) ``` ### iteration You can iterate over streams synchronously or asynchronously in platforms that support it. Synchronous iteration will end when the currently available data is consumed, even if the `end` event has not been reached. In string and buffer mode, the data is concatenated, so unless multiple writes are occurring in the same tick as the `read()`, sync iteration loops will generally only have a single iteration. To consume chunks in this way exactly as they have been written, with no flattening, create the stream with the `{ objectMode: true }` option. ```js const mp = new Minipass({ objectMode: true }) mp.write('a') mp.write('b') for (let letter of mp) { console.log(letter) // a, b } mp.write('c') mp.write('d') for (let letter of mp) { console.log(letter) // c, d } mp.write('e') mp.end() for (let letter of mp) { console.log(letter) // e } for (let letter of mp) { console.log(letter) // nothing } ``` Asynchronous iteration will continue until the end event is reached, consuming all of the data. ```js const mp = new Minipass({ encoding: 'utf8' }) // some source of some data let i = 5 const inter = setInterval(() => { if (i --> 0) mp.write(Buffer.from('foo\n', 'utf8')) else { mp.end() clearInterval(inter) } }, 100) // consume the data with asynchronous iteration async function consume () { for await (let chunk of mp) { console.log(chunk) } return 'ok' } consume().then(res => console.log(res)) // logs `foo\n` 5 times, and then `ok` ```