window.onload = init;

function init() {
    //preload images
	return;   
}

function $(elementID){
	var element = elementID;
	if(typeof element=='string')
		element=document.getElementById(element);

	return element;
}
	 
function hide () {
	for (i = 0; i < arguments.length; i++) {
		var e = $(arguments[i]);
		if (e){
			e.style.display = "none";
		}
	}
}

function show () {
	for (i = 0; i < arguments.length; i++) {
		var e = $(arguments[i]);
		if (e){
			e.style.display = "";
		}
	}
}

function vemail(email) {
    var emailRE = new RegExp("^[a-zA-Z0-9][a-zA-Z0-9_\.\-]+\@[a-zA-Z0-9\-]+\.[a-zA-Z0-9]{2,4}$");
    return emailRE.exec(email);
}

function verlogin() {
	var f = $("logform");
    var e = $("logerr");
    e.innerHTML = "";
    if (!vemail(f.email.value)) {
        e.innerHTML = "invalid email";
        return false;
    }

    if (f.op[1].checked && f.email.value != f.email2.value) {
        e.innerHTML = "emails don't match";
        return false;
    }
	 return true;
}

function toreg() {
    if ($("logform").op[1].checked)
		 show("vemailtxt", "vemail");
    else
		 hide("vemailtxt", "vemail");
}

function tab(obj)
{
	var ul=$("maintab").getElementsByTagName("li");
	for (var i=0; i<ul.length; i++)
		ul[i].className="";
		
	obj.parentNode.className="selected";
}

function showTable(table) {
    var t = $("target");
	 
	 switch (table)
	 {
		 case "pipe":
			 t.innerHTML = pipeTable();
		 break;
		 
		case "oef":
			 t.innerHTML = "<img src='images/oef.gif' ALT='Orifice Expansion Factor' border='0'>";
		 break;
		 
		 case "lsg":
			 t.innerHTML = lsgTable();
		 break;
		 
		 case "cf":
			 t.innerHTML = cfTable();
		 break;
		 
		 case "gsg":
			 t.innerHTML = gsgTable();
		 break;
		 
		 case "cc":
			 t.innerHTML = ccTable();
		 break;
		 
		 case "z":
			 t.innerHTML = zTable();
		 break;
		 
		 case "refliquid":
			t.innerHTML = refLiquid();
		 break;
		 
		 case "refsteam":
			 t.innerHTML = refSteam();
		 break;
		 
		 case "refgas":
			 t.innerHTML = refGas();
		 break;
		 
		 case "satst":
			 t.innerHTML = satSteamTable();
		 break;
		 
		 case "supst":
			 t.innerHTML = "coming soon";
		 break;
		 
		case "comp":
			t.innerHTML = "<span style='font-weight: 700;'>Procedure for determining 'Compressability Factor Z'</span><br />When dealing with gases at relatively low pressure, it is generally acceptable to use the Compressibility Factor Z obtained from <a href=\"JavaScript:showTable('cf', 'innerTarget')\">this table.</a> Otherwise, obtain and note the Critical Pressure (Pc) and Critical Temperature (Tc) from a reference such as <a href=\"JavaScript:showTable('cc', 'innerTarget')\">this one.</a> Then, use <a href=\"JavaScript:showTable('z', 'innerTarget')\">this utility</a> to calculate the Reduced Pressure (Pr) and Reduced Temperature (Tr).<br /><div id='innerTarget' style='width: 100%'></div>";
		break;
		 
		 default:
			 t.innerHTML = "";
    }
}
