function convertToValidPhoneNumber(text) {  
    var result = [];     
    text = text.replace(/^\d{2}-?\d{3}-?\d{3}-?\d{3}$/, "");
    while (text.length >= 6){       
        result.push(text.substring(0, 3));  
        text = text.substring(3);
    }
    if (text.length > 0) result.push(text); 
    return result.join("-");
}

I test this function against 35200123456785 input string.

It gives me like a number like 352-001-234-56785 but I want 35200-12345678-5.

What do I need to do to fix this?

function convertToValidPhoneNumber(text) {  
    var result = [];     
    text = text.replace(/^\d{2}-?\d{3}-?\d{3}-?\d{3}$/, "");
    while (text.length >= 6){       
        result.push(text.substring(0, 3));  
        text = text.substring(3);
    }
    if (text.length > 0) result.push(text); 
    return result.join("-");
}

I test this function against 35200123456785 input string.

It gives me like a number like 352-001-234-56785 but I want 35200-12345678-5.

What do I need to do to fix this?

• javascript
• regex

• 35200123456785 this is my input – Syed Sabhi Xaidi Commented Apr 4, 2015 at 6:52
• do u need an - after 5 and 8 digits? – Rajeshwar Commented Apr 4, 2015 at 7:17
• 1 Try this regex (\d{5})(\d{8})(\d{1}) and then replace function like follow $1-$2-$3 Demo: regex101./r/fR6tX1/1 – Amen Jlili Commented Apr 4, 2015 at 7:39

2 Answers 2

You can use this updated function that uses ^(?=[0-9]{11})([0-9]{5})([0-9]{8})([0-9])$ regex:

• ^ - String start
• (?=[0-9]{11}) - Ensures there are 11 digits in the phone number
• ([0-9]{5}) - First group capturing 5 digits
• ([0-9]{8}) - Second group capturing 8 digits
• ([0-9]) - Third group capturing 1 digit
• $ - String end

Replacement string - "$1-$2-$3" - uses back-references to those capturing groups in the regex by numbers and adds hyphens where you need them to be.

In case you have hyphens inside the input string, you should remove them before.

function convertToValidPhoneNumber(text) {  
    return text = text.replace(/-/g,"").replace(/^(?=[0-9]{11})([0-9]{5})([0-9]{8})([0-9])$/, "$1-$2-$3");
}
document.getElementById("res").innerHTML = convertToValidPhoneNumber("35200123456785") + " and " + convertToValidPhoneNumber("35-200-123-456-785");

<div id="res"/>

  number = this.state.number;
  var expression = /(\D+)/g;
  var npa = "";
  var nxx = "";
  var last4 = "";
  number = number.toString().replace(expression, "");
  npa = number.substr(0, 3);
  nxx = number.substr(3, 3);
  last4 = number.substr(6, 4);
  number = npa + "-" + nxx + "-" + last4