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onChange Event and setinterval

Asked by Craig Hopson,

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Craig Hopson

Posted
Posted

can this be done?


<!DOCTYPE html>
<html>
<head>
<script>
var seconds = 1000;

function test(optvalue) {
   var seconds = optvalue;
   alert(optvalue);

}

window.setInterval(function(){  
var d=new Date();
document.getElementById("output").innerHTML = d;
  }, seconds);
</script>
</head>
<body>
<select name="menu" onchange="test(this.value);">
	<option value="1">1</option>
	<option value="5">5</option>
	<option value="10">10</option>
</select>
<div id="output"></div>
</body>
</html>
[/CODE]

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4 answers to this question

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Grand Master

jamend

Posted
Posted

There's a few issues. First, in test() you're doing var seconds = ...; Because you put var in front of it, it creates a variable within the local scope (which is the test function), and you're not actually changing the var seconds = 1000. Next, setInterval is not going to know or check that the seconds variable changed; it will continue using the interval that you originally gave it. You'd have to clear the existing interval and set a new one if you want to change it.


<script>
var seconds = 1000;
var interval;

function test(optvalue) {
   seconds = optvalue;
   alert(optvalue);
   window.clearInterval(interval);
   window.setInterval(myDateFunction, seconds);
}

var myDateFunction = function(){  
   var d=new Date();
   document.getElementById("output").innerHTML = d;
};

window.setInterval(myDateFunction, seconds);
</script>
[/CODE]

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Craig Hopson

Posted
  • Author
Posted

thanks for the quick reply i tried your example but it didn't work...

[edit]

got it like this


<script>
var seconds;
var interval;
function test(optvalue) {
   seconds = optvalue;
   alert(optvalue);
interval = window.clearInterval(interval);
interval = window.setInterval(myDateFunction, seconds);
}
var myDateFunction = function(){ 
   var d=new Date();
   document.getElementById("output").innerHTML = d;
};
interval = window.setInterval(myDateFunction, seconds);
</script>
[/CODE]

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Grand Master

jamend

Posted
Posted
  On 01/12/2012 at 22:19, Craig Hopson said:

thanks for the quick reply i tried your example but it didn't work

Whoops. Forgot to assign interval = setInterval()


<script>
var seconds = 1000;
var interval;

function test(optvalue) {
   seconds = optvalue;
   alert(optvalue);
   window.clearInterval(interval);
   interval = window.setInterval(myDateFunction, seconds);
}

var myDateFunction = function(){  
   var d=new Date();
   document.getElementById("output").innerHTML = d;
};

interval = window.setInterval(myDateFunction, seconds);
</script>
[/CODE]

Also keep in mind that interval is set in ms, not seconds, so you might not get what you expect with your option values.

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