switch-stream

swap out a stream in-place

example

For the first three lines, this stream uppercases its input with the prelude transform, then it switches to the size transform, which prints the length of each line.

var switcher = require('switch-stream');
var split = require('split');
var through = require('through');
 
var lines = 0;
var prelude = through(function (line) {
    this.queue(line.toString('utf8').toUpperCase() + '\n')
    if (++lines === 3) sw.set(size);
});
 
var size = through(function (line) {
    this.queue(line.length + '\n');
});
 
var sw = switcher(prelude);
process.stdin.pipe(split()).pipe(sw).pipe(process.stdout);

output:

$ echo -e 'one\ntwo\nthree\nfour\nfive\nsix\nseven' | node example/switch.js 
ONE
TWO
THREE
4
4
3
5
0

methods

var switcher = require('switch-stream')

var sw = switcher(initial)

Create a new switch stream sw with an optional initial stream to start with. Input written to sw will be passed to the currently active stream and output from initial will be output on sw.

sw.set(stream)

Set a new stream for sw to pass data to and from.

install

With npm do:

npm install switch-stream

license

MIT