Using ASLEvent in Command Scripts | A Word of Warning

[KVonGit]

ASLEvent works differently in the desktop player than it does online.

In the desktop player, we can call ASLEvent from a script which is run due to a command. This is not the case online.

To test this, here it is online: https://play.textadventures.co.uk/Play.aspx?id=editor/858f774e-b183-4583-b564-b7c8727f89ed%2fASLEvent+Tester+42.aslx

And here is the game's code to test it in the desktop player:

ASLEvent Tester 42.aslx

<!--Saved by Quest 5.8.9010.29474-->
<asl version="580">
  <include ref="English.aslx" />
  <include ref="Core.aslx" />
  <game name="ASLEvent Tester 42">
    <gameid>dcbe6cb5-7fa1-49b3-8a8a-8536c77625d0</gameid>
    <version>0.0.1</version>
    <firstpublished>2024</firstpublished>
    <subtitle>v{game.version}</subtitle>
    <author>KV</author>
    <menufont>Georgia, serif</menufont>
    <attr name="autodescription_youarein_useprefix" type="boolean">false</attr>
  </game>
  <object name="Testing Station">
    <inherit name="editor_room" />
    <isroom />
    <description>{command:test aslevent}</description>
    <usedefaultprefix type="boolean">false</usedefaultprefix>
    <object name="player">
      <inherit name="editor_object" />
      <inherit name="editor_player" />
    </object>
  </object>
  <command name="test_aslevent_cmd">
    <pattern>test aslevent</pattern>
    <script>
      msg ("Calling ASLEvent ...")
      JS.eval ("ASLEvent('OutputText','ASLEvent fired!');")
    </script>
  </command>
</asl>

---

That command will work as expected every time in the desktop player, but never once online.

Desktop

---

Online

---

This is because the WebPlayer app has a different script.

WebPlayer/player.js#L169-L179

function ASLEvent(event, parameter) {
    if (!canSendCommand) return false;
    canSendCommand = false;
    // using setTimeout here to work around a double-submission race condition which seems to only affect Firefox,
    // even though we use "return false" to suppress submission of the form with the Enter key.
    window.setTimeout(function () {
        $("#fldUIMsg").val("event " + event + ";" + parameter);
        $("#cmdSubmit").click();
    }, 100);
    return true;
}

---

Notice that first line of code: if (!canSendCommand) return false;

While scripts are running in response to a command, canSendCommand will be false.

WebPlayer/player.js#L152-L167

function sendCommand(text, metadata) {
    if (_pauseMode || _waitingForSoundToFinish || _waitMode || !canSendCommand) return;
    canSendCommand = false;
    markScrollPosition();
    window.setTimeout(function () {
        $("#fldUITickCount").val(getTickCountAndStopTimer());
        var data = new Object();
        data["command"] = text;
        if (typeof metadata != "undefined") {
            data["metadata"] = metadata;
        }
        $("#fldUIMsg").val("command " + JSON.stringify(data));
        $("#cmdSubmit").click();
    }, 100);
    afterSendCommand();
}

---

Now, you might be thinking what I was thinking the first time I looked at this: afterSendCommand must set canSendCommand to true; right? Nope.

We have two versions of afterSendCommand online. One in the web player, and one for the mobile player. The web player's does nothing at all. It is only there so the function will be defined.

WebPlayer/playerweb.js#L23-L24

function afterSendCommand() {
}

---

The mobile player simply uses it to select the "game" tab after sending a command.¹

WebPlayer/Mobileplayermobile.js#L205-L207

function afterSendCommand() {
    tabSelected("game");
}

---

The pageLoad function is what sets canSendCommand to true after each turn. Each time we send a command online (typing or clicking), pageLoad runs.

WebPlayer/player.js#L11-L14

function pageLoad() {
    // triggered by ASP.NET every page load, including from the AJAX UpdatePanel
    canSendCommand = true;
}

---

So, we can get around this by altering our script in our command to this:

      msg ("Calling ASLEvent ...")
      JS.eval ("canSendCommand = true; ASLEvent('OutputText','ASLEvent fired!');")

---

Now, it will work online.

https://play.textadventures.co.uk/Play.aspx?id=editor/ebe1cc97-6b4c-468f-bb62-7831707e4b27%2fASLEvent+Tester+42.1.aslx

---

For completion, here is the ASLEvent script for the desktop player:

Player/desktopplayer.js#L18-L20

function ASLEvent(event, parameter) {
    UIEvent("ASLEvent", event + ";" + parameter);
}

Footnotes

1. The mobile player has HTML elements that neither of the other platforms have. ↩