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Prototype Periodical Execution

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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:

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>

To understand it in better way you can Try it yourself.


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