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document.write('Function IsValidEmail(emailAddress)
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document.write('\'Declare variables
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document.write('Dim ValidEmail, emailParts, iLoopCounter, emailChar, acceptableChars
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document.write(' ValidEmail = True \'set the default result to True
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document.write('
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document.write(' \'acceptableChars are the characters that we will allow in our email
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document.write('
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document.write(' acceptableChars="abcdefghijklmnopqrstuvwxyz.-_@"
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document.write(' \'use the Split function to create an array with the @ as the separator
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document.write('
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document.write(' \'so if your email was test@tester.com the email would be split into an array
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document.write('
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document.write(' \'with the first array element holding "test" and the second "tester.com"
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document.write(' emailParts = Split(emailAddress, "@")
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document.write(' \'check to make sure that there is only 1 @ and that there are 2 parts
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document.write('
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document.write(' \'remember arrays are zero based
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document.write('
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document.write(' \'Using the UBound function will return the highest element in the array
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document.write(' \'So if it\'s a valid email the UBound function will return 1, i.e. 0 start
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document.write(' if UBound(emailParts) <> 1 Then
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document.write(' ValidEmail = false
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document.write(' Else
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document.write(' \'Check the length of each part of the email address
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document.write('
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document.write(' \'first part can be just one character, 2nd part must be atleast 4
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document.write(' if Len(emailParts(0))<1 OR Len(emailParts(1))<4 Then
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document.write(' ValidEmail = false
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document.write(' End If
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document.write(' \'check first character on the left part isn\'t a "." using Left function
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document.write('
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document.write(' if Left(emailParts(0), 1)="." Then
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document.write(' ValidEmail = false
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document.write(' End If
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document.write(' \'check the last & 2nd character from right part using Right function
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document.write('
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document.write(' if Right(emailParts(1), 1) = "." OR Right(emailParts(1), 2) = "." Then
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document.write(' ValidEmail = false
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document.write(' End If
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document.write(' \'check that there is a . in the second part of the email address - .com
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document.write('
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document.write(' if InStr(emailParts(1), ".") <= 0 Then
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document.write(' ValidEmail = false
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document.write(' End if
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document.write(' \'check that there shouldn\'t be a _ in the second part of the email address
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document.write('
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document.write(' if InStr(emailParts(1), "_") >0 Then
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document.write(' ValidEmail = false
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document.write(' End if
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document.write(' End If
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document.write(' \'loop through each character of email
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document.write('
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document.write(' For iLoopCounter = 1 to Len(emailAddress)
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document.write(' \'Use Lcase & Mid functions, Mid function used to return each individual character
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document.write('
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document.write(' \'in the email, and then Lcase converts it into lowercase
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document.write('
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document.write(' emailChar = Lcase(Mid(emailAddress, iLoopCounter, 1))
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document.write(' \'Check if the emailAddress characters are acceptable
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document.write(' if InStr(acceptableChars, emailChar) = 0 and Not IsNumeric(emailChar) Then
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document.write(' ValidEmail = false
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document.write(' End if
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document.write(' Next
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document.write(' \'check if there is 2 . in a row
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document.write('
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document.write(' if InStr(emailAddress, "..") > 0 Then
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document.write(' ValidEmail=false
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document.write(' End If
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document.write(' \'check if there is @. in a row
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document.write('
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document.write(' if InStr(emailAddress, "@.") > 0 Then
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document.write(' ValidEmail=false
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document.write(' End if
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document.write(' IsValidEmail=ValidEmail
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document.write('End function
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