Phone Number Validation - Using Regular Expression

• Phone Number Validation Tutorial
  • Phone Number Validation - Using Regular Expression

    In forms when asking for phone numbers fields it is a good idea to use client side validation along with your programming language validation. The following example shows how you can do this.

    We have also provided the javascript phone validation for the Internationl Phone number validation, U.S. number and specially for North America Phone number validation.

    Example

    Example of phone validation

    Enter a Phone Number :
    
    

    View Explanation of the Code

    Cut and Paste Code

    Cut 'n' paste code for the above Example

    JavaScript Code

    <script language = "Javascript"> /** * DHTML phone number validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/) */ // Declaring required variables var digits = "0123456789"; // non-digit characters which are allowed in phone numbers var phoneNumberDelimiters = "()- "; // characters which are allowed in international phone numbers // (a leading + is OK) var validWorldPhoneChars = phoneNumberDelimiters + "+"; // Minimum no of digits in an international phone no. var minDigitsInIPhoneNumber = 11; // Maximum no of digits in an america phone no. var maxDigitsInIPhoneNumber = 13; function isInteger(s) { var i; for (i = 0; i < s.length; i++) { // Check that current character is number. var c = s.charAt(i); if (((c < "0") || (c > "9"))) return false; } // All characters are numbers. return true; } function stripCharsInBag(s, bag) { var i; var returnString = ""; // Search through string's characters one by one. // If character is not in bag, append to returnString. for (i = 0; i < s.length; i++) { // Check that current character isn't whitespace. var c = s.charAt(i); if (bag.indexOf(c) == -1) returnString += c; } return returnString; } function trim(s) { var i; var returnString = ""; // Search through string's characters one by one. // If character is not a whitespace, append to returnString. for (i = 0; i < s.length; i++) { // Check that current character isn't whitespace. var c = s.charAt(i); if (c != " ") returnString += c; } return returnString; } function checkInternationalPhone(strPhone){ strPhone=trim(strPhone) //var re = /\(?\d{3}\)?([-\(])\d{3}?([-\)])\d{6}/; var re = /^((\+\d{1,3}([-\(]| )?\(?\d\)?([-\(]| )?\d{1,5})|(\(?\d{2,6}\)?))(-| )?(\d{3,4})(-| )?(\d{4})$/ var OK = re.exec(strPhone); if (!OK) return false } function ValidateForm(){ var Phone=document.frmSample.txtPhone if ((Phone.value==null)||(Phone.value=="")){ alert("Please Enter your Phone Number") Phone.focus() return false } if (checkInternationalPhone(Phone.value)==false){ alert("Please Enter a Valid Phone Number") Phone.value="" Phone.focus() return false } return true } </script>

    
    HTML Code

    <form name="frmSample" method="post" action="#" onSubmit="return ValidateForm()"> <p>Enter a phone number : <input type="text" name="txtPhone"> </p> <p> <input type="submit" name="Submit" value="Submit"> </p> </form>

    Explanation of the Code

    The JavaScript has the following main functions:

    • Function checkInternationalPhone is used to verify if the given value is a possible valid international phone number : This function first removes all non-digit characters which are allowed in phone numbers. These delimiters are declared in the lines (found in the beginning of the code) :
      
      var phoneNumberDelimiters = "()- "
      var validWorldPhoneChars = phoneNumberDelimiters + "+"
      
      Now that all valid delimiters are removed we just check if the remaining value is an integer and that it has at least a certain number of digits (given by the variable 'minDigitsInIPhoneNumber').
      
      
    • Function ValidateForm is used to make sure that the phone number field is not blank and that it is a valid phone number on form submission

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