Uncaught TypeError: Cannot read property 'then' of undefined when calling a function

Question

What's wrong with my script, I get

Uncaught TypeError: Cannot read property 'then' of undefined

This is my script:

<script type="text/javascript" src="jquery-2.1.3.min.js"></script>
<script type="text/javascript">
function connected() {
    $.ajaxSetup({ cache: false });
    $.ajax({
        type:"get",
        url:"cgi-bin/check",
        success:function(data) {
            if (data.indexOf("192.168.1.1:1080")>-1) {
                var audio = new Audio("on.ogg");
                audio.play();
                document.getElementById("output").innerHTML = "Connected";
                clearTimeout(loop);
            }
        }
    });
    loop = setTimeout(connected, 1000);
}
function disconnected() {
    $.ajaxSetup({ cache: false });
    $.ajax({
        type:"get",
        url:"cgi-bin/check",
        success:function(data) {
            document.getElementById("output").innerHTML = "function disconnected ";
            if (data.indexOf("ssh disconnected")>-1) {
                var audio = new Audio("off.ogg");
                audio.play();
                document.getElementById("output").innerHTML = "Disconnected: "+data;
                clearTimeout(loop);
            }
        }
    });
    loop = setTimeout(disconnected, 1000);
}
function notif() {
    var loop;
    $.ajaxSetup({ cache: false });
    $.ajax({
        type:"get",
        url:"cgi-bin/check",
        success:function(data) {
            if (data.indexOf("192.168.1.1:1080")>-1) {
                document.getElementById("output").innerHTML = "It's connected, waiting to disconnect";
                disconnected().then(connected);
            }
            else {
                document.getElementById("output").innerHTML = "It's disconnected, waiting to connect";
                connected().then(disconnected);
            }
        }
    });
}
notif();
</script>
<p id="output"></p>

That is the script to notify me whether my ssh tunnel gets disconnected / connected. It'll play a sound on each occurence.

score 0 · Answer 1 · edited May 23 '17 at 12:23

Unless I am missing something, your disconnected and connected functions do not return anything, and you are trying to do .then() to an undefined value.

.then() is a Promise method

By the look of your code it seems that you do not fully understand how asynchronous things work, so I would suggest you read a few resources on that.

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Synchronous_and_Asynchronous_Requests

Easy to understand definition of "asynchronous event"?

http://rowanmanning.com/posts/javascript-for-beginners-async/

user2182349 · Answer 2 · 2016-03-14T01:08:56.623

0

Ref: http://api.jquery.com/jquery.ajax/

Deprecation Notice: The jqXHR.success(), jqXHR.error(), and jqXHR.complete() callbacks are deprecated as of jQuery 1.8. To prepare your code for their eventual removal, use jqXHR.done(), jqXHR.fail(), and jqXHR.always() instead.

Change your code to look something like this:

$.ajax({
        type:"get",
        url:"cgi-bin/check"}).done(function(data) {} );

You may use done or then. then will catch errors as well as success responses.

edited Mar 14 '16 at 01:08

answered Mar 14 '16 at 00:49

user2182349

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I did what you suggested but I got an error `Uncaught SyntaxError: Unexpected token ) test.php:16` this is my modified script http://pastebin.com/Gk5Zpq5T – Jess Tim Mar 14 '16 at 01:07
I apologize for the syntax error - it has been corrected. The point of my answer was that you shouldn't be using **success**, you need to use **done** or **then**. – user2182349 Mar 14 '16 at 01:09

Uncaught TypeError: Cannot read property 'then' of undefined when calling a function

2 Answers2