@nlib/stream-tap v1.1.1

@nlib/stream-tap

Put taps in a stream pipeline.

Install

npm install @nlib/stream-tap

Usage

Tap

const {PassThrough} = require('stream');
const {Tap} = require('@nlib/stream-tap');

const source = new PassThrough();
const tap = new Tap({isRunning: false});
const received = [];

source
.pipe(tap)
.on('data', (chunk) => {
  received.push(chunk);
});

source.write('1');
// received: []
source.write('2');
// received: []
tap.turnOn();
// received: ['1', '2']
source.write('3');
// received: ['1', '2', '3']
tap.turnOff();
// received: ['1', '2', '3']
source.end('4');
// received: ['1', '2', '3']
tap.turnOn();
// received: ['1', '2', '3', '4']

TapGroup

const {PassThrough} = require('stream');
const {TapGroup} = require('@nlib/stream-tap');

const source1 = new PassThrough();
const source2 = new PassThrough();
const tapGroup = new TapGroup({isRunning: false});
const received1 = [];
const received2 = [];

source1
.pipe(tapGroup.put())
.on('data', (chunk) => {
  received1.push(chunk);
});
source2
.pipe(tapGroup.put())
.on('data', (chunk) => {
  received2.push(chunk);
});

source1.write('1'); source2.write('1');
// received1: [], received2: []
source1.write('2'); source2.write('2');
// received1: [], received2: []
tapGroup.turnOn();
// received1: ['1', '2'], received2: ['1', '2']
source1.write('3'); source2.write('3');
// received1: ['1', '2', '3'], received2: ['1', '2', '3']
tapGroup.turnOff();
// received1: ['1', '2', '3'], received2: ['1', '2', '3']
source1.end('4'); source2.end('4');
// received1: ['1', '2', '3'], received2: ['1', '2', '3']
tap.turnOn();
// received1: ['1', '2', '3', '4'], received2: ['1', '2', '3', '4']

StartingGate with Gulp

const gulp = require('gulp');
const {StartingGate} = require('@nlib/stream-tap');

const gate = new StartingGate();

gulp.src('src/*.js')
.pipe(middleware1) // for example: minify codes
.pipe(middleware2) // rename files with hash string
.pipe(gate.put())
.pipe(gulp.dest('dest'))

gulp.src('src/*.html')
.pipe(gate.put())
.pipe(middleware3) // replace renamed urls
.pipe(gulp.dest('dest'))

Javascript API

require('@nlib/stream-tap') returns {Tap, TapGroup, StartingGate}.

Tap

new Tap({isRunning = false, onFlush = () => {}})

Create a tap. A tap is an instance of stream.Transform. If it is not running (tap.isRunning === false), it buffers all data passed from overlying stream.

• isRunning type: Boolean default: false The initial state of the tap.

• onFlush type: Function default: () => {} The function called in the transform._flush. Note: The finish and end events are emitted when the tap is running after the onFlush is called.

Tap.prototype.isRunning

Type: Boolean (readonly) The state of the tap.

Tap.prototype.turnOn()

Returns: undefined Turn on the tap.

Tap.prototype.turnOff()

Returns: undefined Turn off the tap.

TapGroup

Create a group of taps which creates taps and controls them.

new TapGroup({isRunning = false, onFlush = () => {}})

• isRunning type: Boolean default: false The initial state of tapGroup.

• onFlush type: Function default: () => {} The function called when taps in the group flushes all data.

TapGroup.prototype.isRunning

Type: Boolean (readonly) The state of the taps.

TapGroup.prototype.turnOn()

Returns: undefined Turn on the taps.

TapGroup.prototype.turnOff()

Returns: undefined Turn off the taps.

StartingGate

StartingGate is a sub class of TapGroup. It is turned on automatically when all streams before its taps flush all data.

class StartingGate extends TapGroup {
  constructor() {
    super({
      isRunning: false,
      onFlush(tapGroup) {
        tapGroup.turnOn();
      },
    });
  }
};

LICENSE

MIT