future-stream
Delay the emission of stream events until a future condition is true
Installation
This module is installed via npm:
$ npm install future-streamExample Usage
futureStream.read
This example delays the streaming of a file to stdout by 1 second.
var futureStream = require('future-stream');
var fs = require('fs');
function makeStream() {
return fs.createReadStream('/etc/passwd', { encoding: 'utf8' });
}
var start = Date.now();
function condition() {
// true after 1 second
return (Date.now() - start) > 1000;
}
var s = futureStream(makeStream, condition);
s.pipe(process.stdout);futureStream.write
This example delays the writing to a file by 1 second
var futureStream = require('future-stream');
var fs = require('fs');
function makeStream() {
return fs.createWriteStream('/tmp/junk', { encoding: 'utf8' });
}
var start = Date.now();
function condition(data) {
// true after 1 second
return (Date.now() - start) > 1000;
}
var s = futureStream.write(makeStream, condition);
// these writes won't be written for 1 second
s.write('hello ');
s.write('world');
s.end();NB: The condition function for writes also will pass in the data being written allowing you to delay writes for specific data items.
For example:
var futureStream = require('future-stream');
var fs = require('fs');
function makeStream() {
return fs.createWriteStream('/tmp/junk', { encoding: 'utf8' });
}
var start = Date.now();
function condition(data) {
// when data is 'delay', delay the write for one second
if (data == 'delay') {
return (Date.now() - start) > 1000;
} else {
return true;
}
}
var s = futureStream.write(makeStream, condition);
s.write('delay');
s.write('not delayed');
s.end();