Passing variables between functions

Question

I have two functions, one that makes an Ajax request when the user loads the page, and one that will run every 5 or so seconds to update something. Using the first function, I can output a variable that I need to use in the second function.

function insert_last_ten() {
    $.ajax({
       url: 'freeshout/chatlog.php',
       success: function(data) {
         $("#inner-wrap").html(data);
         var first_child = $("#inner-wrap :first-child").html();
         var value = first_child.match(/(value)=["']?((?:.(?!["']?\s+(?:\S+)=|[>"']))+.)["']?/);
         var realtime = value[2];
       }
     });
    }

Basically, I need to use realtime to do something else in another function. For the sake of simplicity, let's pretend this is the second function:

function update() {
    alert(realtime);
}

How could I go about making that work?

Can you move realtime out to a more public scope?

jocull
– jocull

2011-01-24 21:38:15 +00:00
Commented Jan 24, 2011 at 21:38 — jocull
– jocull, Commented Jan 24, 2011 at 21:38
Making realtime a global variable would be the easy way.

Marc B
– Marc B

2011-01-24 21:39:00 +00:00
Commented Jan 24, 2011 at 21:39 — Marc B
– Marc B, Commented Jan 24, 2011 at 21:39

Oswald · Accepted Answer · 2011-01-24 23:15:10Z

2

In the success callback, cancel the timeout and start a new one using the updated value. You can pass the timeout identifier to insert_last_ten via argument and the success callback will pick it up via closure:

function createUpdateTimer(value, interval) {
    return setTimout(
      function () {
        alert(value); // The created function knows what value is due to closure
      }, interval);
}

function insert_last_ten(timer) {
    $.ajax({
        url: 'freeshout/chatlog.php',
        success: function(data) {
            $("#inner-wrap").html(data);
            var first_child = $("#inner-wrap :first-child").html();
            var value = first_child.match(/(value)=["']?((?:.(?!["']?\s+(?:\S+)=|[>"']))+.)["']?/);
            var realtime = value[2];
            cancelTimer(timer); // This callbac knows what timer is due to closure
            timer = createUpdateTimer(realtime, 500);
        }
    });
}

// Start the timer:
var timer = createUpdateTimer('initial value', 500);

// Make ajax request:
insert_last_ten(timer);

Note that I am only beginning to familiarize myself with the good parts of JavaScript. This code is untested.

edited Jan 24, 2011 at 23:15

answered Jan 24, 2011 at 21:39

Oswald

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2 Comments

Andrew Over a year ago

How would I go about that? I checked through jQuery docs and searched around, and couldn't really find out what you mean. =/

Oswald Over a year ago

@Andrew: I updated my answer with an example. Closures are not in the jQuery documentation, because it's a JavaScript feature, not a jQuery feature.

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