Javascript Form Validator | All Together Now

Below we have taken the HTML form code and the new function formValidator and plugged in all the other form validation functions taught in this lesson that are referenced in formValidator.

JavaScript/HTML Form validator...
The following code should be write in between //script tag
function formValidator()
{
// Make quick references to our fields
var firstname = document.getElementById('firstname');
var addr = document.getElementById('addr');
var zip = document.getElementById('zip');
var state = document.getElementById('state');
var username = document.getElementById('username');
var email = document.getElementById('email');
// Check each input in the order that it appears in the form!
if(isAlphabet(firstname, "Please enter only letters for your name"))
{
if(isAlphanumeric(addr, "Numbers and Letters Only for Address"))
{
if(isNumeric(zip, "Please enter a valid zip code"))
{
if(madeSelection(state, "Please Choose a State"))
{
if(lengthRestriction(username, 6, 8))
{
if(emailValidator(email, "Please enter a valid email address"))
{
return true;
}
}
}
}
}
}
return false;
}
function isEmpty(elem, helperMsg)
{
if(elem.value.length == 0)
{
alert(helperMsg);
elem.focus();
// set the focus to this input return true;
}
return false;
}
function isNumeric(elem, helperMsg)
{
var numericExpression = /^[0-9]+$/;
if(elem.value.match(numericExpression))
{
return true;
}
else
{
alert(helperMsg);
elem.focus();
return false;
}
}
function isAlphabet(elem, helperMsg)
{
var alphaExp = /^[a-zA-Z]+$/;
if(elem.value.match(alphaExp))
{
return true;
}
else
{
alert(helperMsg);
elem.focus();
return false;
}
}
function isAlphanumeric(elem, helperMsg)
{
var alphaExp = /^[0-9a-zA-Z]+$/;
if(elem.value.match(alphaExp))
{
return true;
}
else
{
alert(helperMsg);
elem.focus();
return false;
}
}
function lengthRestriction(elem, min, max)
{
var uInput = elem.value;
if(uInput.length >= min && uInput.length <= max)
{
return true;
}
else
{
alert("Please enter between " +min+ " and " +max+ " characters");
elem.focus();
return false;
}
}
function madeSelection(elem, helperMsg)
{
if(elem.value == "Please Choose")
{
alert(helperMsg);
elem.focus();
return false;
}
else
{
return true;
}
}
function emailValidator(elem, helperMsg)
{
var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
if(elem.value.match(emailExp))
{
return true;
}
else
{
alert(helperMsg);
elem.focus();
return false;
}
}