// implodeFormArray(form name : String, form element name : String, delimiter : String);
function implodeFormArray(f, e, del) {
	var form	= document.forms[f];
	if (typeof(form.elements[e].value) != "undefined") {
		if (form.elements[e].checked) return form.elements[e].value;
		else return '';
	} else {
		var output	= '';
		var len		= form.elements[e].length;
		for(var i=0;i<len;i++) {
			if (form.elements[e][i].checked) {
				output+= (output == '' ? '':del) + form.elements[e][i].value;
			}
		}
		return output;
	}
}

I frequently pass an array of elements from an HTML form to PHP, normally a list of checkboxes for removing database records.  This will loop through an array of  checkbox's with the same name & build a delimited string from the checked values.  After I have the values in a delimited string I normally have a hidden field which holds the string & explode it on the PHP side.

Implode Form Element Array

form, html, array

JavaScript