how to use jQuery ajax calls with node.js

Question

This is similar to Stream data with Node.js, but I don\'t feel that question was answered sufficiently.

I\'m trying to use a jQuery ajax call (get, load, getJSON) to

Answer 1

Use something like the following on the server side:

http.createServer(function (request, response) {
    if (request.headers['x-requested-with'] == 'XMLHttpRequest') {
        // handle async request
        var u = url.parse(request.url, true); //not needed

        response.writeHead(200, {'content-type':'text/json'})
        response.end(JSON.stringify(some_array.slice(1, 10))) //send elements 1 to 10
    } else {
        // handle sync request (by server index.html)
        if (request.url == '/') {
            response.writeHead(200, {'content-type': 'text/html'})
            util.pump(fs.createReadStream('index.html'), response)
        } 
        else 
        {
            // 404 error
        }
    }
}).listen(31337)

Answer 2

I suppose your html page is hosted on a different port. Same origin policy requires in most browsers that the loaded file be on the same port than the loading file.

Answer 3

Thanks to yojimbo for his answer. To add to his sample, I wanted to use the jquery method $.getJSON which puts a random callback in the query string so I also wanted to parse that out in the Node.js. I also wanted to pass an object back and use the stringify function.

This is my Client Side code.

$.getJSON("http://localhost:8124/dummy?action=dostuff&callback=?",
function(data){
  alert(data);
},
function(jqXHR, textStatus, errorThrown) {
    alert('error ' + textStatus + " " + errorThrown);
});

This is my Server side Node.js

var http = require('http');
var querystring = require('querystring');
var url = require('url');

http.createServer(function (req, res) {
    //grab the callback from the query string   
    var pquery = querystring.parse(url.parse(req.url).query);   
    var callback = (pquery.callback ? pquery.callback : '');

    //we probably want to send an object back in response to the request
    var returnObject = {message: "Hello World!"};
    var returnObjectString = JSON.stringify(returnObject);

    //push back the response including the callback shenanigans
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end(callback + '(\'' + returnObjectString + '\')');
}).listen(8124);

Answer 4

If your simple test page is located on other protocol/domain/port than your hello world node.js example you are doing cross-domain requests and violating same origin policy therefore your jQuery ajax calls (get and load) are failing silently. To get this working cross-domain you should use JSONP based format. For example node.js code:

var http = require('http');

http.createServer(function (req, res) {
    console.log('request received');
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('_testcb(\'{"message": "Hello world!"}\')');
}).listen(8124);

and client side JavaScript/jQuery:

$(document).ready(function() {
    $.ajax({
        url: 'http://192.168.1.103:8124/',
        dataType: "jsonp",
        jsonpCallback: "_testcb",
        cache: false,
        timeout: 5000,
        success: function(data) {
            $("#test").append(data);
        },
        error: function(jqXHR, textStatus, errorThrown) {
            alert('error ' + textStatus + " " + errorThrown);
        }
    });
});

There are also other ways how to get this working, for example by setting up reverse proxy or build your web application entirely with framework like express.