Ok so here's the scenario, Suppose you have some sort of form with a couple of checkboxes and you want the user to select at least one before submitting, rather than write a bunch of iteration code, jQuery offers a really easy way to do it.

function setHiddenAction(element) {
    var okToSubmit = false;
    //A. Make sure that the user selects at least one item before they Request an Action
    if( $("input:checkbox:checked").length > 0 ) okToSubmit = true;
    //B. Set the Hidden Value to the Users Requested Action
    $("#action").attr("value", element.value)
    //C. Either Submit or give an Error Message
    if( okToSubmit ) {
    } else {
        alert( "Please select at least one item" );