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86 lines
2.5 KiB
Markdown
86 lines
2.5 KiB
Markdown
9 years ago
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through2-spy
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============
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[](https://nodei.co/npm/through2-sink/)
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This is a super thin wrapper around [through2](http://npm.im/through2) for creating simple 'terminus' streams, that do nothing but look at the chunk received.
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This module is heavily based on Bryce B. Baril's [through2-spy](https://www.npmjs.com/package/through2-spy), with the `.push` call removed. Why? So that you can have the same functionality at the *end* of a pipeline, without buffering everything up. It was originally written to help implement progress events in [bhttp](https://www.npmjs.com/package/bhttp). If you were to just use `through2-spy` for this, then [this](https://github.com/joyent/node/issues/14477) would happen.
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Pass a function to run as each chunk goes through your stream pipeline. Return an Error to abort the pipeline.
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```js
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var sink = require("through2-sink")
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var count = 0
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var countChunks = sink(function (chunk) {
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count++
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})
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// vs. with through2:
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var countChunks = through2(function (chunk, encoding, callback) {
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count++
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return callback()
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})
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// Then use your sink:
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source.pipe(countChunks)
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// Additionally accepts `wantStrings` argument to conver buffers into strings
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var nsaregex = /(open source)|(foss)|(node\.js)|(mods are asleep)|(post sinks)/i
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var prizm = sink({wantStrings: true}, function (str) {
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var buggyWiretap = str.match(nsaregex)
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if (buggyWiretap) {
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this.emit("OMGTERRIST", buggyWiretap[0], str)
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}
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})
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prizm.on("OMGTERRIST", sendDrone(/* ... */))
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internet.pipe(prizm) // can't have the terrists getting their packets!
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// Return an Error to abort the pipeline
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var Meter = sink.ctor({maxBytes: 1024, bytes: 0}, function (chunk) {
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this.options.bytes += chunk.length
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if (this.options.bytes >= this.options.maxBytes) return new Error("Over 1024 byte limit!")
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})
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var meter = new Meter()
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```
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API
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---
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`require("through2-sink")([options], fn)`
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---
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Create a `through2-sink` instance that will call `fn(chunk)` and then silently pass through data downstream.
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`require("through2-sink").ctor([options], fn)`
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---
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Create a `through2-sink` Type that can be instantiated via `new Type()` or `Type()` to create reusable sinks.
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`require("through2-sink").obj([options], fn)`
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---
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Create a `through2-sink` that defaults to `objectMode = true`.
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`require("through2-sink").objCtor([options], fn)`
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---
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Create a `through2-sink` Type that defaults to `objectMode = true`.
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Options
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-------
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* wantStrings: Automatically call chunk.toString() for the super lazy.
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* all other through2 options
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LICENSE
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=======
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MIT
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