//Shortcut for commonly used document.getElementById method.
function id(i){
	return document.getElementById(i);
}

//Evaluates the form on page 1. If fruit shares are being ordered by no fruit share pickup location is selected, put up a warning and prevent use of the continue button; diddo for veggie shares. If no shares have been selected for order, prevent use of continue button but do not display any warning. Runs on page load and any time a form element is changed, modifying warnings and the continue button as needed.
function evalorderform(){
	if ((id("standard_fruit").selectedIndex != 0 || id("extended_fruit").selectedIndex != 0) && (id("fruit_loc").selectedIndex == 0)) {
		id("fruit_location_text").className = "important";
		var fruit_location = false;
	} else {
		id("fruit_location_text").className = "";
		var fruit_location = true;
	}
	if ((id("small_veggie").selectedIndex != 0 || id("large_veggie").selectedIndex != 0) && (id("veggie_loc").selectedIndex == 0)) {
		id("veggie_location_text").className = "important";
		var veggie_location = false;
	} else {
		id("veggie_location_text").className = "";
		var veggie_location = true;
	}
	if (id("standard_fruit").selectedIndex == 0 && id("extended_fruit").selectedIndex == 0 && id("small_veggie").selectedIndex == 0 && id("large_veggie").selectedIndex == 0) {
		var items_ordered = false;
	} else {
		var items_ordered = true;
	}
	if (fruit_location && veggie_location && items_ordered) {
		id("continue").disabled = false;
	} else {
		id("continue").disabled = true;
	}
}

//Adds appropriate event handlers unobtrusivly; function called on page load.
function init(){
	if (id("orderform")) {
		evalorderform();
		id("standard_fruit").onchange = evalorderform;
		id("extended_fruit").onchange = evalorderform;
		id("small_veggie").onchange = evalorderform;
		id("large_veggie").onchange = evalorderform;
		id("fruit_loc").onchange = evalorderform;
		id("veggie_loc").onchange = evalorderform;
	}
}

//Initiates the script, using either W3C or IE methods.
if (window.addEventListener) {
	window.addEventListener("load", init, false);
} else {
	window.attachEvent("onload", init);
}