Javascript xmlhttp get request to nodejs server returns nothing

Question

Before I begin I'd like to tell all of you that I made a lot of searching for solution of this problem on my own.

Here is my nodejs server:

var http = require('http');
http.createServer(function (req, res) {
    console.log("Recived request url " + req.url);
    var sname = req.url.search("name");
    if(sname != -1){
        sname = sname + "name".length + 1;
        var from = sname;
        while(req.url[sname] != '?' && sname<req.url.length){
            sname++;
        }
        var name = req.url.substring(from,sname);
        console.log("Returning parameter of name - " + name);
        res.writeHead(200, {'Content-Type': 'text/plain'});
        res.end(name+'\n');
    }
    else{
        res.writeHead(200, {'Content-Type': 'text/plain'});
        res.end('Error - ask about name\n');
    }

}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');

It listens on port 1337 and if request url is correct it returns some string.

Here is my javascript code asking nodejs for answer.

function httpGet(theUrl){
    var xmlHttp = null;
    xmlHttp = new XMLHttpRequest();
    xmlHttp.open( "GET", theUrl, true );
    xmlHttp.send( null );
    return xmlHttp.responseText;
}

var url = httpGet("http://127.0.0.1:1337/?name=Mateusz");

setTimeout(function(){
    document.getElementById("actualnewsspace").innerHTML=url;
    var xurl = httpGet("http://127.0.0.1:1337/?"+url);
},5000)

returned xmlHttp.responseText is blank. Why? That's my question.

That's what my nodejs server has to say in this matter

Recived request url /?name=Mateusz
Returning parameter of name - Mateusz
Recived request url /?

If I curl my server it returns mi proper value.

Just as a tip: take a look at url.parse, it's a really easy way to parse URL's and query strings (var query = require('url').parse(req.url, true).query; var sname = query.name;) — robertklep
– robertklep, Commented May 20, 2013 at 9:52
Another tip: using the XMLHttpRequest object directly is a pain in the neck, and doesn't add any worthwhile understanding in my opinion. I'd recommend using jQuery or similar to avoid bugs writing your own http client code. — Richard Marr
– Richard Marr, Commented May 20, 2013 at 10:54

Quentin · Accepted Answer · 2013-05-20 08:53:27Z

3

xmlHttp.responseText hasn't been populated when you return it. Ajax is Asynchronous.

See Using XMLHttpRequest and bind an event handler to listen for when the HTTP response has arrived and process the data in that.

answered May 20, 2013 at 8:53

Quentin

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1 Comment

Mateusz Zając Over a year ago

Can't accept the answer yet. It seems that you are right. I added a timeout to a return and I get a return that is undefined but I get something at last. I will try to bind an event a handler or maybe try to get a reaction on status change. Now I have something to work on. Thank you!

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