在不使用正则表达式的情况下验证具有不同格式的电话号码

Question

In JavaScript, I need validate phone numbers without using regular expressions (must be with string manipulation). The phone numbers have to be in one of the following formats:

1. 123-456-7890
2. 1234567890
3. (123)4567890
4. (123)456-7890

Then I must also provide an alert if the phone number isn't in one of the formats listed above.

I have only been able to manage to get #2 working, which looks something like this:

function len(gth) 
{
if (gth.value.length != 10) 
    {
        alert("Telephone numbers MUST be 10 digits!");
    }
}

which down in the HTML it would call up to the function:

<p>Phone: &nbsp;&nbsp; <input id = "phone" onblur="len(this)" name = "Phone" size = "20" type = "text" maxlength = "10"> </p>

Answer 1

Since you need a solution without regex, I believe this should work.

 const phones = [ '123-456-7890', '1234567890', '(123)4567890', '(123)456-7890', '+61(123) 456-7890', '12345', '))))01/34$89.77(99' ] function len(gth) { if (gth.substring(3, 4) == '-' && gth.substring(7, 8) == '-') // 123-456-7890 gth = gth.replace('-', '').replace('-', ''); else if (gth.substring(0, 1) == '(' && gth.substring(4, 5) == ')' && gth.substring(8, 9) == '-') // (123)456-7890 gth = gth.replace('(', '').replace(')', '').replace('-', ''); else if (gth.substring(0, 1) == '(' && gth.substring(4, 5) == ')') // (123)4567890 gth = gth.replace('(', '').replace(')', ''); if (!isNaN(gth) && gth.length == 10) { return true; } alert("Telephone numbers:" + gth + " MUST be 10 digits!"); } phones.forEach(len) 

Answer 2

I would replace the numbers with something like x , then check against predefined patterns:

function check(num) {
  let pattern = '';
  for (let i = 0; i < num.length; i++) {
    pattern += num[i] >= '0' && num[i] <= '9' ? 'x' : num[i];
  }

  return ['xxx-xxx-xxxx', 'xxxxxxxxxx', '(xxx)xxxxxxx', '(xxx)xxx-xxxx']
    .indexOf(pattern) >= 0;
}

For extra credit, find the bug in the above program.

However, you don't really need to do any of this. You should be able to use the pattern attribute on the input element. That will also provide a better user experience. For instance, you can style the input element using the :invalid pseudo-class, by putting a red border around it for example, to give the user real-time feedback that their input is not valid. Yes, that takes a regular expression--what was your reason for not wanting to use a regular expression again?

Answer 3

You can make it manually be:

• Checking string size if it is the expected or not
• split the string to char array then parse them as integers inside a try block if numberFormatException is thrown it should be a bracket ( ) or -

Answer 4

Basic example of extracting the input data to Array

 function test() { var phnTest = document.getElementById('phone').value; var strArray = []; strArray = phnTest.split(''); document.getElementById('p').innerHTML = strArray; } 

  <form action="demo_form.asp"> Phone <input id="phone" type="text" name="phone"><br> <input type="button" value='Submit' onclick="test()"> </form> <p id='p'></p> 

This is dependent on how the data is structured, if you need to search a body of text and so on, but basics would be...

If it's a simple pull from an <input> , grab the data...

Take the input data, and generate an array with each character. You could then test, say strArray[3] , for a dash or a dot. If not present, it can continue along to check for seven numbers in a row and so on.

This is going to be extremely consuming and require a number of conditionals to be checked. I assume the "without RegEx" is a requirement for a project or such, if not, recommend learning and using RegEx.

Hope this gets you going.

Answer 5

This is my attempt. The key is creating an array from the string then filtering out any non numerical characters. It would be easier to use regular expression though. just

number.replace(/(\D+)/g, '')

 const numbers = [ '123-456-7890', '1234567890', '(123)4567890', '(123)456-7890', '+61(123) 456-7890', '12345', '))))01/34$89.77(99' ] // validate a phone number function validate(number) { const digits = clean(number) console.log({ number, digits, length: digits.length, pass: digits.length === 10 }) } // remove any non digits from the number function clean(number) { return Array.from(number).filter(char => { return !isNaN(char) && char !== ' ' }).join('') } numbers.forEach(validate)