Validating Common Form Input - Part 4

Validating phone numbers

This one is far more simple than validating names as phone numbers only consist of digits.

To validate a phone number 8 digits long

 1 function validate(form) {
 2   // Regular expression for a phone number
 3   // \d is equivalent to [0-9]
 4   var rgx = /^\s*\d{8}\s*$/;
 5   if(!rgx.test(form.elements.phone.value))
 6     return false;
 7   return true;
 8 }
function validate(form) {
  // Regular expression for a phone number
  // \d is equivalent to [0-9]
  var rgx = /^\s*\d{8}\s*$/;
  if(!rgx.test(form.elements.phone.value))
    return false;
  return true;
}

Very simply indeed. Not all countries have phone numbers of uniform length. To test for a number which has at least 7 digits

 1 function validate(form) {
 2   // Regular expression for a phone number
 3   // \d is equivalent to [0-9]
 4   var rgx = /^\s*\d{7,}\s*$/;
 5   if(!rgx.test(form.elements.phone.value))
 6     return false;
 7   return true;
 8 }
function validate(form) {
  // Regular expression for a phone number
  // \d is equivalent to [0-9]
  var rgx = /^\s*\d{7,}\s*$/;
  if(!rgx.test(form.elements.phone.value))
    return false;
  return true;
}

Phone numbers can be entered in many ways - some write 12345678 others write 12 34 56 78. Too allow for any number of spaces and weird scenarios

 1 function validate(form) {
 2   // Regular expression for a phone number
 3   // \d is equivalent to [0-9]
 4   var rgx = /^(\s*\d+\s*)+$/;
 5   if(!rgx.test(form.elements.phone.value))
 6     return false;
 7   return true;
 8 }
function validate(form) {
  // Regular expression for a phone number
  // \d is equivalent to [0-9]
  var rgx = /^(\s*\d+\s*)+$/;
  if(!rgx.test(form.elements.phone.value))
    return false;
  return true;
}

but again we loose the ability to count the number of digits. The only way to do this is first remove any spaces then do the validation

 1 function validate(form) {
 2   // Shortcut to save writing
 3   var elm = form.elements;
 4   // Remove spaces
 5   elm.phone.value = elm.phone.value.replace(/\s*/g,'');
 6   // Regular expression for a phone number
 7   // \d is equivalent to [0-9]
 8   var rgx = /^\d{5,11}$/;
 9   if(!rgx.test(elm.phone.value))
10     return false;
11   return true;
12 }
function validate(form) {
  // Shortcut to save writing
  var elm = form.elements;
  // Remove spaces
  elm.phone.value = elm.phone.value.replace(/\s*/g,'');
  // Regular expression for a phone number
  // \d is equivalent to [0-9]
  var rgx = /^\d{5,11}$/;
  if(!rgx.test(elm.phone.value))
    return false;
  return true;
}

The above will validate any phone number consisting of between 5 and 11 digits no matter how many spaces the user choose to enter.

Some times we need to allow for international dialing codes. These always start with a plus. We apply the same tactic to first remove any spaces and then check for an optional +

 1 function validate(form) {
 2   // Shortcut to save writing
 3   var elm = form.elements;
 4   // Remove spaces
 5   elm.phone.value = elm.phone.value.replace(/\s*/g,'');
 6   // Regular expression for a phone number
 7   // \d is equivalent to [0-9]
 8   var rgx = /^\+?\d{11}$/;
 9   if(!rgx.test(elm.phone.value))
10     return false;
11   return true;
12 }
function validate(form) {
  // Shortcut to save writing
  var elm = form.elements;
  // Remove spaces
  elm.phone.value = elm.phone.value.replace(/\s*/g,'');
  // Regular expression for a phone number
  // \d is equivalent to [0-9]
  var rgx = /^\+?\d{11}$/;
  if(!rgx.test(elm.phone.value))
    return false;
  return true;
}

This will validate a number of exactly 11 digits with an optional leading +.

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