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Many times it is required to execute a function many times after a certain period of time. For example, you may want to refresh your screen after a given time. Prototype provides a simple mechanism to implement it using PeriodicalExecuter object.
The advantage provided by PeriodicalExecuter is that it shields you against multiple parallel executions of the callback function.
Creating a PeriodicalExecuter
The constructor takes two arguments −
- The callback function.
- The interval (in seconds) between executions.
Once launched, a PeriodicalExecuter triggers indefinitely, until the page unloads or the executer is stopped using stop() method.
Example
Following is the example which will pop up a dialogue box after every 5 seconds untill you will stop it by pressing “cancel” button.
<html>
<head>
<title>Prototype examples</title>
<script type = "text/javascript" src = "/javascript/prototype.js"></script>
<script>
function startExec() {
new PeriodicalExecuter(function(pe) {
if (!confirm(''Want me to annoy you again later?''))
pe.stop();
}, 5);
}
</script>
</head>
<body>
<p>Click start button to start periodic executer:</p>
<br />
<br />
<input type = "button" value = "start" onclick = "startExec();"/>
</body>
</html>
Output
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