CODE EXAMPLE FOR JAVASCRIPT

js password check

var code = document.getElementById("password");

var strengthbar = document.getElementById("meter");
var display = document.getElementsByClassName("textbox")[0];

code.addEventListener("keyup", function() {
  checkpassword(code.value);
});


function checkpassword(password) {
  var strength = 0;
  if (password.match(/[a-z]+/)) {
    strength += 1;
  }
  if (password.match(/[A-Z]+/)) {
    strength += 1;
  }
  if (password.match(/[0-9]+/)) {
    strength += 1;
  }
  if (password.match(/[$@#&!]+/)) {
    strength += 1;

  }

  if (password.length < 6) {
    display.innerHTML = "minimum number of characters is 6";
  }

  if (password.length > 12) {
    display.innerHTML = "maximum number of characters is 12";
  }

  switch (strength) {
    case 0:
      strengthbar.value = 0;
      break;

    case 1:
      strengthbar.value = 25;
      break;

    case 2:
      strengthbar.value = 50;
      break;

    case 3:
      strengthbar.value = 75;
      break;

    case 4:
      strengthbar.value = 100;
      break;
  }
}