// validates that the field value string has one or more characters in it
//message is optional, if omit,change the elem color to red
function isNotEmpty(elem,errorMessage) {
    clearElementError(elem);

	  var str = elem.value;
    var re = /.+/;
    if(!str.match(re)) {
    		showElementError(elem, errorMessage);
        setTimeout("focusElement('" + elem.form.name + "', '" + elem.name + "')", 0);
        return false;
    } else {
        return true;
    }
}

//validates that the entry is a positive or negative number
//message is optional, if omit,change the elem color to red
function isNumber(elem,errorMessage) {
    clearElementError(elem);

	  var str = elem.value;
    var re = /^[-]?\d*\.?\d*$/;
    str = str.toString();
    if (str=="" || !re.test(str)) {
        showElementError(elem, errorMessage);
        setTimeout("focusElement('" + elem.form.name + "', '" + elem.name + "')", 0);
        return false;
    }
    return true;
}

//validate with true/false expression
function isTrue(elem,expression,errorMessage){
    clearElementError(elem);

    if (!expression) {
        showElementError(elem, errorMessage);
        setTimeout("focusElement('" + elem.form.name + "', '" + elem.name + "')", 0);
        return false;
    }
    return true;
	}

// validates that the entry is formatted as an e-mail address
function isEMailAddr(elem,errorMessage) {
    clearElementError(elem);

  	var str = elem.value;
    var re = /^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/;
    if (!str.match(re)) {
        showElementError(elem, errorMessage);
        setTimeout("focusElement('" + elem.form.name + "', '" + elem.name + "')", 0);
        return false;
    } else {
        return true;
    }
}

// validate that the user made a selection other than default
function isChosen(select) {
    if (select.selectedIndex == 0) {
        alert("Please make a choice from the list.");
        return false;
    } else {
        return true;
    }
}

// validate that the user has checked one of the radio buttons
function isValidRadio(radio) {
    var valid = false;
    for (var i = 0; i < radio.length; i++) {
        if (radio[i].checked) {
            return true;
        }
    }
    alert("Make a choice from the radio buttons.");
    return false;
}

function focusElement(formName, elemName) {
    var elem = document.forms[formName].elements[elemName];
    elem.focus();
    elem.select();
}

function showElementError(elem, errorMessage) {
		if (errorMessage==null) {
			elem.style.backgroundColor="red";
		} else {
      alert(errorMessage);
		}
}

function clearElementError(elem) {
		if (elem.style.backgroundColor=="red") {
		    elem.style.backgroundColor="white";
		}
}