Formats phone number inputs

phone-formatter.js

(function () {
  $('#format-me').on('keydown', function (event) {
    var text = event.target.value
    var regex = /^\(\d{3}\)\s\d{3}-\d{4}$/

    // if it's valid do nothing
    if (regex.test(text)) { return }

    // strip the input down to numbers only
    text = text.replace(/\D/g, '')

    // if someone hits backspace just return
    if (event.keyCode === 8) {
      event.preventDefault()
      text = text.slice(0, -1)
    }

    // `(${ text.slice(0,3) }) ${ text.slice(3,6) }-${ text.slice(6,10) }`
    // format the text
    var parsed = ''
    if (text.length > 0) {parsed += `(${ text.slice(0,3) }`}
    if (text.length > 2) { parsed += `) ` }
    parsed += text.slice(3,6)
    if (text.length > 5) { parsed += `-` }
    parsed += text.slice(6,10)

    event.target.value = parsed
  })
})()