1694. Reformat Phone Number.js

// You are given a phone number as a string number. number consists of digits, spaces ' ', and/or dashes '-'.

// You would like to reformat the phone number in a certain manner. Firstly, remove all spaces and dashes. Then, group the digits from left to right into blocks of length 3 until there are 4 or fewer digits. The final digits are then grouped as follows:

// 2 digits: A single block of length 2.
// 3 digits: A single block of length 3.
// 4 digits: Two blocks of length 2 each.
// The blocks are then joined by dashes. Notice that the reformatting process should never produce any blocks of length 1 and produce at most two blocks of length 2.

// Return the phone number after formatting.

// Example 1:

// Input: number = "1-23-45 6"
// Output: "123-456"
// Explanation: The digits are "123456".
// Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is "123".
// Step 2: There are 3 digits remaining, so put them in a single block of length 3. The 2nd block is "456".
// Joining the blocks gives "123-456".
// Example 2:

// Input: number = "123 4-567"
// Output: "123-45-67"
// Explanation: The digits are "1234567".
// Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is "123".
// Step 2: There are 4 digits left, so split them into two blocks of length 2. The blocks are "45" and "67".
// Joining the blocks gives "123-45-67".
// Example 3:

// Input: number = "123 4-5678"
// Output: "123-456-78"
// Explanation: The digits are "12345678".
// Step 1: The 1st block is "123".
// Step 2: The 2nd block is "456".
// Step 3: There are 2 digits left, so put them in a single block of length 2. The 3rd block is "78".
// Joining the blocks gives "123-456-78".

const reformatNumber = number => {
	return number.replace(/\D/g, '').replace(/(...?(?=..))/g, '$1-')
}