countdown timer in javascript [duplicate]

This question already has answers here: Closed 10 years ago.

Possible Duplicate:

How to create a JQuery Clock / Timer

Does anyone knows countdown timer usi开发者_高级运维ng javascript??

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Using pure javascript, you would use the setTimeout method in a manner similar to this (treat this code as pseudocode, it is just to show the concept, I do not think it will work as-is):

countdown = function()
{
   var current = parseInt(document.getElementById("countdownBox").innerHTML);
   document.getElementById("countdownSpan").innerHTML = current;

   if (current > 0)
   {
       setTimeout('countdown()', 1000); // run every second
   }
}

You would start the countdown by writing something in the element with id countdownBox and calling countdown() for the first time.

Edit: note that the setTimeout method will tend to lose seconds if used this way - if you want real precision you will most likely have to synchronize externally every once in a while.

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The following will alert wow in 5 seconds.

setTimeout ( 'wow()', 5000 );

function wow() { alert('wow'); }