Array and setTimeout -- stymied

**nunofyer bzness** · 09-03-2009 12:33 PM

Hello folks,

I am stymied by the behavior of the following code fragment. It actually works in IE5, but I get error messages in FF3:

==================
in <head>
==================
function timingloop(itemarray,opast,opaend, speed,steps, diff,loops)
{
ib=0;
jb=0;
var ti=[];
var tp=[];

loops--;
//alert(loops);
for( jb=0;jb<=3;jb++){
for( ib=0;ib<=2;ib++){
alert('itemarray ='+ib + itemarray[ib]);
ti[ib]=setTimeout("zxcEleOpacity("+itemarray[ib]+","+opaend+","+opast+","+speed+","+steps+")",diff+1000+ib*8000+jb*30000);
tp[ib]=setTimeout("zxcEleOpacity("+itemarray[ib]+","+opaend+","+opast+","+speed+","+steps+")",diff+5000*ib+8000+jb*30000);
}
}
}

==================
in <body>:
==================

<body>onload="zxcEleOpacity('Test1',10),zxcEleOpacity('Test2',10),zxcEleOpacity('Test3',10)" style="background-color:black">

<div id="Test1" style="position:relative;width:200px;height:150px;" >
<img alt="" src="columbine_1.jpg" />
</div>

<div id="Test2" style="position:absolute;width:200px;height:150px;left:200px;top=400px" >
<img alt="" src="DSCF0076.jpg" />
</div>

<div id="Test3" style="position:absolute;width:200px;height:150px;left:400px;top=200px" >
<img alt="" src="DSCF0185.jpg" />
</div>

<script type="text/javascript">

var itemarray = [];
itemarray[0]='Test1';
itemarray[1]='Test2';
itemarray[2]='Test3';

alert(itemarray[0]);
alert(itemarray[1]);
alert(itemarray[2]);
alert('array size = '+itemarray.length);

//zxcEleOpacity('Test1',0);
//zxcEleOpacity('Test2',0);
//initial display

timingloop(itemarray,0,100,1000,10,1000,5);

====================

The "zxc" functions are from a script I got on the web.

The idea is simple: I have a few elements on the page (with ids 'Test1', 'Test2', etc. whose appearance (opacity I want to change.

I am setting up an array with the IDs (itemarray), and pass that into a function (timingloop), which calls setTimeout a few times to effect the opacity changes. I think the problem is in the way that I am trying to pass the arguments to the xcEleOpacity() function in the setTimeout function. The function takes 5 parmameters, of which the first one is the Id of the element. FF3 reports an error: 'Test1 is not defined'. IE5 does not report back an error and runs the script the way I want it.

It's probably the way I need to format the arguments for the setTimeout function, but I have tried numerous different ways, and I can't figure it out.

Thanks for your help.

**nunofyer bzness** · 09-03-2009 12:59 PM

Ok, quick update:

I just found out about "closure" and tried this:

ti[ib]=setTimeout(function(){zxcEleOpacity(itemarray[ib],opast,opaend,speed,steps)},diff+1000+ib*8000+jb*30000);

Errors in both IE5 and FF3.

Then I tried

ti[ib]=setTimeout(function(){zxcEleOpacity('Test1',opast,opaend,speed,steps)},diff+1000+ib*8000+jb*30000);

and it works in both FF3 and IE5 !!!

Now, how do I pass the value of itemarray[1] to the function? I have tried to enclose itemarray[ib] in quotationmarks (which does not amke sense to me) and it doesn't work.

Also, I heard that the "closure" can lead to a memory leak, which can be prevented by declaring the parameter=null. Do I have to do that for each parameter separately, or is "parameter=null" sufficient for all parmaters?

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