setInterval inside setTimeout not working... why?

Question

I'm trying to make an element change opacity based on a series of values pre-set on an array. That action should begin after the user clicks a button AND the system waits for a second.

Here's what I got:

<script>
$(function() {
$("#Listening").click(function() {

    setTimeout(triggerListening, 1000);
    function triggerListening()
    {
        document.getElementById("listening").className = "listeningIn";
    }

    setTimeout(triggerUserTalking, 2000);
    function triggerUserTalking()
    {

        var audioSim = [3, 2, 7, 15, 15, 16, 15, 7, 7, 3, 8, 8, 17, 17, 20, 20, 21, 21, 17, 17, 13, 13, 12, 12, 13, 13, 16, 16, 18, 18, 17, 17, 16, 16, 14, 10, 11, 11, 15, 15, 16, 16, 15, 15, 14, 14, 13, 13, 13, 13, 15, 15, 23, 44, 55, 55, 56, 55, 44, 44, 33, 29, 31, 31, 42, 50, 60, 63, 60, 54, 39, 39, 30, 28, 30, 30, 33, 33, 36, 39, 38, 38, 33, 16, 6, 6, 5, 7, 18, 18, 28, 31, 28, 28, 26, 26, 23, 22, 23, 23, 25, 28, 28, 28, 27, 27, 28, 28, 28, 28, 28, 28, 27, 27, 28, 28, 35, 35, 43, 43, 49, 54, 56, 55, 43, 36, 26, 28, 31, 52, 65, 70, 68, 68, 51, 45, 41, 41, 38, 40, 49, 49, 57, 58, 58, 31, 42, 42, 46, 51, 55, 55, 54, 42, 33, 31, 37, 37, 45, 46, 42, 42, 37, 38, 38, 41, 41, 44, 44, 46, 48, 47, 47, 43, 44, 44, 47, 47, 49, 49, 48, 45, 44, 44, 44, 44, 45, 45, 44, 44, 43, 39, 36, 34, 35, 59, 59, 85, 93, 98, 98, 100, 95, 67, 67, 43, 36, 34, 34, 39, 51, 62, 62, 68, 76, 75, 75, 50, 36, 27, 20, 18, 36, 57, 57, 52, 48, 43, 44, 49, 50, 50, 49];

        var i = 0;

        window.setInterval('step()', 20)

        function step() {
            var element = document.getElementById("listening");
            element.style.opacity = "0." + audioSim[i];
            i++;
            if (i == audioSim.length) i = triggerStopTalking;
        }

        function triggerStopTalking()
        {
            document.getElementById("listening").className = "listeningOut";
        }

    }                   

});
});
</script>

This works fine expect the changing opacity part...

User clicks Listening and after 1 second the listening object appears on the screen by toggling the "listeningIn" class... after another second that element should change opacity a bunch of times based on the values inside "audioSim"... but it doesn't...

I've tested the setInterval code in a separate html file and it works fine... so I'm thinking I can't have a setInterval inside a setTimeout function? Help?

SLaks · Accepted Answer · 2012-11-27 22:38:24Z

3

You're passing a string to setInverval.
Don't do that.

setInterval is evaling your string in the global scope; step() is a local variable. Therefore, it doesn't find anything.

Instead, you need to pass the function itself:

setInterval(step);

answered Nov 27, 2012 at 22:38

SLaks

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Jim Blackler · Accepted Answer · 2012-11-27 22:38:33Z

3

Instead of

window.setInterval('step()', 20);

try

window.setInterval(step, 20);

I believe the text version will be evaluated on the global scope where step may not exist.

answered Nov 27, 2012 at 22:38

Jim Blackler

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Comments

RobG · Accepted Answer · 2012-11-27 22:39:51Z

3

In the line:

> window.setInterval('step()', 20)

setInterval is executed in a global context, but step is declared inside another context that window can't access. Change it to:

setInterval(step, 20)

so that you pass a reference to the function instead.

answered Nov 27, 2012 at 22:39

RobG

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