两个xmlhttprequest中的第二个调用不起作用

Question

I've read a lot of how to try and make two xmlhttprequest in parallel, but it looks like something doesn't quite work.
I have 1 php file. which includes 2 .js files.
The first runs xmlhttprequest every 3 seconds.
I want the second to run on demand, but whenever i trigger it, it returns with status 4 but the responseText is always empty. (the PHP file prints with no question, i even tried to put on the PHP file just window.open('1') to see that the file is called and its not).

Here is the first JS :

var req1 = createXMLHttpRequest2();

var user_redirected = false;

function createXMLHttpRequest2() {
var ua2;
if(window.XMLHttpRequest) {
    try {
    ua2 = new XMLHttpRequest();
    } catch(e) {
    ua2 = false;
    }
} else if(window.ActiveXObject) {
    try {
    ua2 = new ActiveXObject("Microsoft.XMLHTTP");
    } catch(e) {
    ua2 = false;
    }
}
return ua2;
}

function set_user_redirected_false() {
user_redirected = false;
}

function get_user_redirected() {
return user_redirected;
}

function handleResponse(username, game_id, isInvitation) {
    if(req1.readyState == 4 && req1.status==200) {
        var response = req1.responseText;
        if (response == "true") {
            // Ask to set the game_accepted var to 1 (user is redirected and not leaving)
            user_redirected = true;
            if (isInvitation == "true") {
                window.location.href = "game.php?game_id="+game_id+"&position=2";
            } else {
                window.location.href = "game.php?game_id="+game_id+"&position=1";
            }
        }
        else {
            setTimeout(function(){sendRequest();}, 3000);
        }
    }
}

function sendRequest() {
    user_redirected = false;
    var username = "";
    var game_id = -1;
    var isInvitation = "false";
    username = document.getElementById("username").value;
    game_id = document.getElementById("game_id").value;
    isInvitation = document.getElementById("invitation").value;
    if (isInvitation == "true") {
        req1.open('GET', 'check_for_inviter.php?username='+username+'&game_id='+game_id ,true);
    } else {
        req1.open('GET', 'check_for_opponent.php?username='+username+'&game_id='+game_id,true);
    }
    req1.onreadystatechange = function(){handleResponse(username, game_id, isInvitation);};
    req1.send(null);
}

This is the second JS file :

function createXMLHttpRequest() {
    var ua;
    if(window.XMLHttpRequest) {
        try {
            ua = new XMLHttpRequest();
        } catch(e) {
            ua = false;
        }
    } else if(window.ActiveXObject) {
        try {
            ua = new ActiveXObject("Microsoft.XMLHTTP");
        } catch(e) {
            ua = false;
        }
    }
    return ua;
}

function delete_waiting_games(username) {
    var req2 = createXMLHttpRequest();
    req2.open('GET', 'delete_waiting_games_for_username.php');
    req2.onreadystatechange = function(){
        window.open(req2.readyState+'&'+req2.responseText);
    };
    req2.send(null);
}

As you can see i open a new window to see the response and the ready state (just for testing) and i always get status 4 and empty responseText.

Thanks.

Answer 1

Use setTimeout to separate the calls, and with to encapsulate the XMLHTTPRequest :

function xhr()
  {
  with(new XMLHttpRequest)
    {
    open("GET",{},true);
    setRequestHeader("Foo", "Bar");
    send("");
    onreadystatechange = handler;
    }
  }

function handler(event)
 {
 !!event.target && !!event.target.readyState && event.target.readyState === 4 && ( console.log(event) );
 }

setTimeout(xhr, 500);
setTimeout(xhr, 1000);