Nodejs send data in gzip using zlib

Question

I tried to send the text in gzip, but I don't know how. In the examples the code uses fs, but I don't want to send a text file, just a string.

const zlib = require('zlib');
const http = require('http');

http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/html', 'Content-Encoding': 'gzip'});

    const text = "Hello World!";
    res.end(text);

}).listen(80);

Answer 1

You're half way there. I can heartily agree that the documentation isn't quite up to snuff on how to do this;

const zlib = require('zlib');
const http = require('http');

http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/html', 'Content-Encoding': 'gzip'});

    const text = "Hello World!";
    const buf = new Buffer(text, 'utf-8');   // Choose encoding for the string.
    zlib.gzip(buf, function (_, result) {  // The callback will give you the 
        res.end(result);                     // result, so just send it.
    });
}).listen(80);

A simplification would be not to use the Buffer;

http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/html', 'Content-Encoding': 'gzip'});

    const text = "Hello World!";
    zlib.gzip(text, function (_, result) {  // The callback will give you the 
      res.end(result);                     // result, so just send it.
    });
}).listen(80);

...and it seems to send UTF-8 by default. However, I personally prefer to walk on the safe side when there is no default behavior that makes more sense than others and I can't immediately confirm it with documentation.

Similarly, in case you need to pass a JSON object instead:

const data = {'hello':'swateek!'}

res.writeHead(200, {'Content-Type': 'application/json', 'Content-Encoding': 'gzip'});
const buf = new Buffer(JSON.stringify(data), 'utf-8');
zlib.gzip(buf, function (_, result) {
    res.end(result);
});