A node.js through stream that does basic streaming text search and replace and is chunk boundary friendly.
Install via npm:
$ npm install replacestream
Say we want to do a search and replace over the following file:
// happybirthday.txt
Happy birthday to you!
Happy birthday to you!
Happy birthday to dear Liza!
Happy birthday to you!
var replaceStream = require('replacestream')
, fs = require('fs')
, path = require('path');
// Replace all the instances of 'birthday' with 'earthday'
fs.createReadStream(path.join(__dirname, 'happybirthday.txt'))
.pipe(replaceStream('birthday', 'earthday'))
.pipe(process.stdout);
Running this will print out:
$ node simple.js
Happy earthday to you!
Happy earthday to you!
Happy earthday to dear Liza!
Happy earthday to you!
You can also limit the number of replaces to first n
:
// Replace the first 2 of the instances of 'birthday' with 'earthday'
fs.createReadStream(path.join(__dirname, 'happybirthday.txt'))
.pipe(replaceStream('birthday', 'earthday', { limit: 2 } ))
.pipe(process.stdout);
Which would output:
$ node simple.js
Happy earthday to you!
Happy earthday to you!
Happy birthday to dear Liza!
Happy birthday to you!
Here's the same example, but kicked off from a HTTP server:
// server.js
var http = require('http')
, fs = require('fs')
, path = require('path')
, replaceStream = require('replacestream');
var app = function (req, res) {
if (req.url.match(/^\/happybirthday\.txt$/)) {
res.writeHead(200, { 'Content-Type': 'text/plain' });
fs.createReadStream(path.join(__dirname, 'happybirthday.txt'))
.pipe(replaceStream('birthday', 'earthday'))
.pipe(res);
} else {
res.writeHead(200, { 'Content-Type': 'text/plain' });
res.end('File not found');
}
};
var server = http.createServer(app).listen(3000);
When you request the file:
$ curl -i "http://localhost:3000/happybirthday.txt"
HTTP/1.1 200 OK
Content-Type: text/plain
Date: Mon, 08 Jul 2013 06:45:21 GMT
Connection: keep-alive
Transfer-Encoding: chunked
Happy earthday to you!
Happy earthday to you!
Happy earthday to dear Liza!
Happy earthday to you!
NB: If your readable Stream that you're piping through the replacestream
is
paused, then you may have to call the .resume()
method on it.
You can also change the text encoding of the search and replace by setting an encoding property on the options object:
// Replace the first 2 of the instances of 'birthday' with 'earthday'
fs.createReadStream(path.join(__dirname, 'happybirthday.txt'))
.pipe(replaceStream('birthday', 'earthday', { limit: 2, encoding: 'ascii' } ))
.pipe(process.stdout);
By default the encoding will be set to 'utf8'.