我似乎无法弄清楚正则表达式

Question

I have the following code. I am trying to have the regular express test the phone number for validation. With the current argument the function should return positive, but it doesn't and I can't figure out why.

function telephoneCheck(str) {

  let reg = /^[\d]{0,1}[\w]{0,1}[(]{0,1}[\d]{3}[-)\w]{0,2}[\d]{3}[-\w]{0,1}[\d]/;
  return reg.test(str);
  
}

console.log("function: " + telephoneCheck("1 (555) 555-5555"));

Can anyone see what I am missing?

Answer 1

First, replace all the \\w (Matches any letter, digit or underscore) with \\s (Matches any space, tab or newline character). I believe you don't won't letter in phone number. Second, you need to add a quantifier {0,4} to the end of your Regex, just like you already did in other positions of the Regex.

So the final Regex will be ^[\\d]{0,1}[\\s]{0,1}[(]{0,1}[\\d]{3}[-)\\s]{0,2}[\\d]{3}[-\\s]{0,1}[\\d]{0,4}

Answer 2

Because your regex is nonsense.

1. No need for [] for single group ( [\\d]{0,1} can be just \\d?
2. \\w does not match spaces, just [a-z0-9] in general case
3. You match starting ( but ending ) can be followed by - or any \\w

 function telephoneCheck(str) { let reg = /^\\d?\\s?\\(?[\\d-]+\\)?\\s?\\d+/; return reg.test(str); } console.log("function: " + telephoneCheck("1 (555) 555-5555"));

Answer 3

1. You need to replace \\w with \\s for whitespace
2. You need to escape parenthesis \\( and \\)
3. You need to change [-)\\w]{0,2} to [-\\)]{0,1}[\\s]{0,1} unless you want the unorthodox 1 (555)-555-5555 to be true.
4. The final [\\d] should be [\\d]{4} since you want exactly 4 digits at the end.

 function telephoneCheck(str) { let reg = /^[\\d]{0,1}[\\s]{0,1}[\\(]{0,1}[\\d]{3}[-\\)]{0,1}[\\s]{0,1}[\\d]{3}[-\\s]{0,1}[\\d]{4}/; return reg.test(str); } console.log("function: " + telephoneCheck("1 (555)555-5555"));