How to validate phone number in HTML form

Question

I have a form and would like to see if the user filled the input with a correct number or not. The number must contains 10 digits and the two first digits should be equal to 05 or 06 . Can anyone help me how to do this in PHP or in JavaScript please?

Answer 1

According to comments and example phone number that you given, this code will validating number of digits and first two numbers of your country, i just replaced + with 0, for sure they won't enter plus.

$tel = '0512345678';

if(preg_match("/^0[5|6][0-9]{8}$/", $tel)) {
    echo "valid";
} else {
    echo "invalid";
}

Answer 2

Would you like to validate the phone number on the server or in the client (user's web browser)? In the first case you should use PHP, in the latter case a JavaScript function.

PHP:

function isValidPhoneNumber($number) {
  return preg_match('/^0[5|6][0-9]{8}$/', $number);
}

JavaScript:

function isValidPhoneNumber(number) {
  return /^0[5|6][0-9]{8}$/.test(number);
}