SO jQuery Fiddle

Test Fiddle mainly for SO Questions jQuery 1.4.3, UI 1.8.5

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.5/themes/ui-lightness/jquery-ui.css">

JavaScript

var str = "xxx_yyy";
var startsWith = str.indexOf("xxx_") === 0;
alert(startsWith);
var stringArray = str.split("_");
alert(stringArray);