// Splintered striper 1.3
// reworking of Zebra Tables and similar methods which works not only for tables and even/odd rows,
// but as a general DOM means of assigning any number of classes to children of a parent element.
// Patrick H. Lauke aka redux / www.splintered.co.uk
// Distributed under the Creative Commons Attribution-ShareAlike license - http://creativecommons.org/licenses/by-sa/2.0/


/*
 * Summary:      Core experiment function that applies any number of classes to all child elements
 *               contained in all occurences of a parent element (either with or without a specific class)
 * Parameters:   parentElementTag - parent tag name
 *               parentElementClass - class assigned to the parent; if null, all parentElementTag elements will be affected
 *               childElementTag -  tag name of the child elements to apply the styles to
 *               styleClasses - comma separated list of any number of style classes (using 2 classes gives the classic "zebra" effect)
 * Return:       none
 * 
 * onload="striper('tbody','striped','tr','odd,even'); 
 */
function striper(parentElementTag, parentElementClass, childElementTag, styleClasses)
{
    var i=0,currentParent,currentChild;
    // capability and sanity check
    if ((document.getElementsByTagName)&&(parentElementTag)&&(childElementTag)&&(styleClasses)) {
        // turn the comma separate list of classes into an array
        var styles = styleClasses.split(',');
        // get an array of all parent tags
        var parentItems = document.getElementsByTagName(parentElementTag);
        // loop through all parent elements
        while (currentParent = parentItems[i++]) {
            // if parentElementClass was null, or if the current parent's class matches the specified class
            if ((parentElementClass == null)||(currentParent.className == parentElementClass)) {
                var j=0,k=0;
                // get all child elements in the current parent element
                var childItems = currentParent.getElementsByTagName(childElementTag);
                // loop through all child elements
                while (currentChild = childItems[j++]) {
                    // based on the current element and the number of styles in the array, work out which class to apply
                    k = (j+(styles.length-1)) % styles.length;
                    // add the class to the child element - if any other classes were already present, they're kept intact
                    currentChild.className = currentChild.className+" "+styles[k];
                }
            }
        }
    }
}