Format SSN onkeyup

README.md

Source : https://stackoverflow.com/questions/7685175/autoformat-ssn-while-entering-the-number

formatSSN.js

function(event) {
  var val = event.target.value.replace(/\D/g, '');
  var newVal = '';

  if(val.length > 4) {
    this.value = val;
  }

  if((val.length > 3) && (val.length < 6)) {
    newVal += val.substr(0, 3) + '-';
    val = val.substr(3);
  }

  if (val.length > 5) {
    newVal += val.substr(0, 3) + '-';
    newVal += val.substr(3, 2) + '-';
    val = val.substr(5);
  }

  newVal += val;
  event.target.value = newVal;
};