Synchronous vs Asynchronous - How do I even?

[Ellie]

My game is fucked, because it relies solely on one function that is used everywhere and that function is now deprecated.

I don't understand how to make it work asynchronously.

Basically my function is Ajax but synchronous:

ajaxRequest = function(param) {

  var retrievedData = "";

  var get_params = param;

  var xhttp = new XMLHttpRequest();

 

  xhttp.onreadystatechange = function() {

    if (xhttp.readyState == 4 && xhttp.status == 200) {

      retrievedData = xhttp.responseText;

    }

  }

 

  xhttp.open("GET", "http://website.web/a.php" + "?" + get_params + "&rand=" + Math.random(), true);

  xhttp.send();

 

  return retrievedData;

};

Such that I can use this function like so:


if (variable from web) == 1, do this
if (variable from web) == true, do that
Set (variable on web) to 7

Now I can do the third asynchronously, that's fine. But the first two require a response immediately, and I don't want or need the game to continue in that time.

For example, game switches is replaced with this function, so when a switch is used I do something like this (but with error handling and such):

get_switch = function(t, variable) {

  $return = ajaxRequest("a=gs&t=" + t + "&i=" + variable);

  return $return;

}

conditonal branch: script: {

get_switch(1);

}


Now that they're saying is that I have to handle this asynchronously instead. Now that doesn't make sense in the context of a conditonal branch.

Say I have a chest. I want to find out if the chest has been opened, so I ask the server (get_switch(1)). I don't want or need the script to continue processing until the response comes through, because I need the value for the rest of the script to make any kind of sense.


But I can't do this synchronously any more.

I don't even understand how this is supposed to work. I guess the answer is it doesn't?

Isn't this going to kill a lot of online games?

 

[ZenVirZan]

Hacky way: load the switch states on map load and poll the server for it every now and then
Proper way: provide callbacks to your jquery ajax calls (ie. success) to continue the code after the call instead, typically done using anonymous functions