node-http-proxy-json/README.md

for node-http-proxy transform the response json from the proxied server.

# node-http-proxy-json [![Build Status](https://travis-ci.org/langjt/node-http-proxy-json.svg?branch=master)](https://travis-ci.org/langjt/node-http-proxy-json)
  for [node-http-proxy](https://github.com/nodejitsu/node-http-proxy) transform the response json from the proxied server.

## Installation

```  
npm install node-http-proxy-json
```

## Motivation
  When using [node-http-proxy](https://github.com/nodejitsu/node-http-proxy) need to modify the response. If your proxy server returns HTML/XML document, you can try [Harmon](https://github.com/No9/harmon).
  But sometimes the proxy server only returns the JSON. For example, call API from the server. Usually the server will compress the data.
  So before using this repository, confirm your server compression format, currently only supports **gzip**、**deflate** and **uncompressed**.
  If you need other compression formats, please create a new Issue, and I will try to achieve it as much as possible.

## Use Cases

#### Simulation server using gzip compression

```js
var zlib = require('zlib');
var http = require('http');
var httpProxy = require('http-proxy');
var modifyResponse = require('node-http-proxy-json');

// Create a proxy server
var proxy = httpProxy.createProxyServer({
    target: 'http://localhost:5001'
});

// Listen for the `proxyRes` event on `proxy`.
proxy.on('proxyRes', function (proxyRes, req, res) {
    modifyResponse(res, proxyRes, function (body) {
        if (body) {
            // modify some information
            body.age = 2;
            delete body.version;
        }
        return body; // return value can be a promise
    });
});

// Create your server and then proxies the request
var server = http.createServer(function (req, res) {
    proxy.web(req, res);
}).listen(5000);

// Create your target server
var targetServer = http.createServer(function (req, res) {

    // Create gzipped content
    var gzip = zlib.Gzip();
    var _write = res.write;
    var _end = res.end;

    gzip.on('data', function (buf) {
        _write.call(res, buf);
    });
    gzip.on('end', function () {
        _end.call(res);
    });

    res.write = function (data) {
        gzip.write(data);
    };
    res.end = function () {
        gzip.end();
    };

    res.writeHead(200, {'Content-Type': 'application/json', 'Content-Encoding': 'gzip'});
    res.write(JSON.stringify({name: 'node-http-proxy-json', age: 1, version: '1.0.0'}));
    res.end();
}).listen(5001);
```

#### Simulation server using deflate compression

```js
var zlib = require('zlib');
var http = require('http');
var httpProxy = require('http-proxy');
var modifyResponse = require('../');

// Create a proxy server
var proxy = httpProxy.createProxyServer({
    target: 'http://localhost:5001'
});

// Listen for the `proxyRes` event on `proxy`.
proxy.on('proxyRes', function (proxyRes, req, res) {
    modifyResponse(res, proxyRes, function (body) {
        if (body) {
            // modify some information
            body.age = 2;
            delete body.version;
        }
        return body; // return value can be a promise
    });
});

// Create your server and then proxies the request
var server = http.createServer(function (req, res) {
    proxy.web(req, res);
}).listen(5000);

// Create your target server
var targetServer = http.createServer(function (req, res) {

    // Create deflated content
    var deflate = zlib.Deflate();
    var _write = res.write;
    var _end = res.end;

    deflate.on('data', function (buf) {
        _write.call(res, buf);
    });
    deflate.on('end', function () {
        _end.call(res);
    });

    res.write = function (data) {
        deflate.write(data);
    };
    res.end = function () {
        deflate.end();
    };

    res.writeHead(200, {'Content-Type': 'application/json', 'Content-Encoding': 'deflate'});
    res.write(JSON.stringify({name: 'node-http-proxy-json', age: 1, version: '1.0.0'}));
    res.end();
}).listen(5001);
```

#### Server does not enable compression

```js
var http = require('http');
var httpProxy = require('http-proxy');
var modifyResponse = require('../');

// Create a proxy server
var proxy = httpProxy.createProxyServer({
    target: 'http://localhost:5001'
});

// Listen for the `proxyRes` event on `proxy`.
proxy.on('proxyRes', function (proxyRes, req, res) {
    modifyResponse(res, proxyRes, function (body) {
        if (body) {
            // modify some information
            body.age = 2;
            delete body.version;
        }
        return body; // return value can be a promise
    });
});

// Create your server and then proxies the request
var server = http.createServer(function (req, res) {
    proxy.web(req, res);
}).listen(5000);

// Create your target server
var targetServer = http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'application/json', 'Content-Encoding': 'deflate'});
    res.write(JSON.stringify({name: 'node-http-proxy-json', age: 1, version: '1.0.0'}));
    res.end();
}).listen(5001);
```

## Tests

  To run the test suite, first install the dependencies, then run `npm test`:

```bash
$ npm install
$ npm test
```

## License

  [MIT](http://opensource.org/licenses/MIT)