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My HTML page becomes unresponsive when doing javascript validation


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My HTML page is having password input field when I try to input values to the password input field then the page becomes unresponsive after entering more than 30 to 40 characters. Below is the code which I am using. This issue I am having in all web browsers. Even if I change the minimum length and all other like lower, upper, number and symbol value to 50 then also the same problem persist. I am new to javascript, Kindly do the needful.

    <!DOCTYPE html>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    /* Style all input fields */
    input {
      width: 100%;
      padding: 12px;
      border: 1px solid #ccc;
      border-radius: 4px;
      box-sizing: border-box;
      margin-top: 6px;
      margin-bottom: 16px;

    /* Style the submit button */
    input[type=submit] {
      background-color: #4CAF50;
      color: white;

    /* Style the container for inputs */
    .container {
      background-color: #f1f1f1;
      padding: 20px;

    /* The message box is shown when the user clicks on the password field */
    #message {
      background: #f1f1f1;
      color: #000;
      position: relative;
      padding: 20px;
      margin-top: 10px;

    #message p {
      padding: 10px 35px;
      font-size: 18px;

    /* Add a green text color and a checkmark when the requirements are right */
    .valid {
      color: green;

    .valid:before {
      position: relative;
      left: -35px;
      content: "✔";

    /* Add a red text color and an "x" when the requirements are wrong */
    .invalid {
      color: red;

    .invalid:before {
      position: relative;
      left: -35px;
      content: "✖";

    <p>Try to submit the form.</p>

    <div class="container">
      <form action="/action_page.php">
        <label for="usrname">Username</label>
        <input type="text" id="usrname" name="usrname" required>

        <label for="psw">Password</label>
        <input type="password" id="psw" name="psw" pattern="(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,}" title="Must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters" required>
        <input type="submit" value="Submit">

    <div id="message">
      <h3>Password must contain the following:</h3>
      <p id="letter" class="invalid">199 <b>lowercase</b> letter</p>
      <p id="capital" class="invalid">199 <b>capital (uppercase)</b> letter</p>
      <p id="number" class="invalid">199 <b>number</b></p>
      <p id="length" class="invalid">Minimum <b>199 characters</b></p>
    var myInput = document.getElementById("psw");
    var letter = document.getElementById("letter");
    var capital = document.getElementById("capital");
    var number = document.getElementById("number");
    var length = document.getElementById("length");

    // When the user clicks on the password field, show the message box
    myInput.onfocus = function() {
      document.getElementById("message").style.display = "block";

    // When the user clicks outside of the password field, hide the message box
    myInput.onblur = function() {
      document.getElementById("message").style.display = "none";

    // When the user starts to type something inside the password field
    myInput.onkeyup = function() {
      // Validate lowercase letters
      var lowerCaseLetters = new RegExp('(?:[a-z].*){' + 199 + '}', 'g')
      if(myInput.value.match(lowerCaseLetters)) {  
      } else {
      // Validate capital letters
      var upperCaseLetters = new RegExp('(?:[A-Z].*){' + 199 + '}', 'g')
      if(myInput.value.match(upperCaseLetters)) {  
      } else {

      // Validate numbers
      var numbers = new RegExp('(?:[0-9].*){' + 199 + '}', 'g')
      if(myInput.value.match(numbers)) {  
      } else {
      // Validate length
      if(myInput.value.length >= 199) {
      } else {



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