//clears the input field when clicked
function clearInput(el) {if (el.defaultValue==el.value) el.value = "";}


//checks to see if value entered is numeric
function isNumeric(sText){
var ValidChars = "0123456789";
var IsNumber = true;var Char;

for (i = 0; i < sText.length && IsNumber == true; i++){
Char = sText.charAt(i); 

if(ValidChars.indexOf(Char) == -1){
IsNumber = false;
}
}
return IsNumber;
}



//validates number entered in zip field
function validateZipCode(field,zipID) {
var zipField = document.getElementById(zipID);
if (field.length < 5 || field.length > 5 || field == "00000" || field == "99999") {
alert("Enter a valid 5 digit zip code.");
zipField.focus();
return false;
} 

if(!isNumeric(field)){
alert("Please enter a valid zip code.");
zipField.focus();
return false;
}
return true;
}