Monday, July 19, 2004

JavaScript Function to Validate Zip codes (valid zipcode)

This function returns True if a Zipcode is a validly formatted U.S. Zip code, false if it is not.


/*
ValidZipCode - true for valid zip codes, false for invalid ones
*/
function ValidZipCode(ZipCode)
{
//Your zip code must contain 5 or 9 digits.
// 9 digit zip codes should contain no spaces and a
// hyphen before the last 4 digits.

var stringValue = new String(ZipCode);
var stringLength = stringValue.length;

if ((stringLength!=5)&&(stringLength!=9)&&(stringLength!=10))
{
return false;
}

if(stringLength==5)
{

for (var i = 0; i < stringLength; i++)
{
value = stringValue.charAt(i)
if (!((value >= 0) && (value <=9)))
{
return false;
}
}
}

if(stringLength==9)
{
for (var i = 0; i < stringLength; i++)
{
value = stringValue.charAt(i)
if (!((value >= 0) && (value <=9)))
{
return false;
}
}
}

if(stringLength==10)
{
var zip=stringValue.substring(0,5)
var symbol=stringValue.substring(5,6)
var plus4=stringValue.substring(6,10)

if(symbol!="-")
{
return false;

}


for (var i = 0; i < zip.length; i++)
{
value = zip.charAt(i)
if (!((value >= 0) && (value <=9)))
{
return false;
}
}
for (var i = 0; i < plus4.length; i++)
{
value = plus4.charAt(i)
if (!((value >= 0) && (value <=9)))
{
return false;
}
}

}
return true;
}