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 transfer data between a page and a node.js server. I can hit the address from my browser and see 'Hello World!", but when I try this from my page, it fails and shows that I get no response back. I setup a simple test page and hello world example to test this:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <title>get test</title> 
</head>
<body>
    <h1>Get Test</h1>
    <div id="test"></div>

    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.js"></script>
    <script>
        $(document).ready(function() {
            //alert($('h1').length);
            $('#test').load('http://192.168.1.103:8124/');
            //$.get('http://192.168.1.103:8124/', function(data) {                
            //  alert(data);
            //});
        });
    </script>
</body>
</html>

and

var http = require('http');

http.createServer(function (req, res) {
    console.log('request received');
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World\n');
}).listen(8124);
1
70
5/23/2017 12:32:20 PM

Accepted Answer

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.

86
3/21/2011 10:05:52 AM

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);

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