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Note: Paramters in the bracket are always optional
Here is the detail of parameters:
datestring : A string representing a date
Number of milliseconds since midnight of January 1, 1970.
var msecs = Date.parse("Jul 8, 2008");
document.write( "Number of milliseconds from 1970: " + msecs );
This will produce following result :
Number of milliseconds from 1970: 1215455400000
To understand it in better way you can Try it yourself.