index.html

<!doctype html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.2/css/bootstrap.min.css" integrity="sha384-Smlep5jCw/wG7hdkwQ/Z5nLIefveQRIY9nfy6xoR1uRYBtpZgI6339F5dgvm/e9B" crossorigin="anonymous">
    <link rel="stylesheet" href="style.css">
    <title>PasswordGenerator</title>
    <script src="passGenerate.js"></script>
  </head>
  <body>
   <div class="container">
    <form action="" name="passGen">
       <div class="col-xs-12">
        <input type="text" name="output" class="out" disabled>
        <input type="button" class="btn btn-success btn-block myBtn" onclick="generatepassword(this.form.length.value)" value="Generate password">
        <div class="col-xs-10"> <strong class="pass">Password Length:</strong></div>
        <div class="col-xs-2"> <input type="number" name="length" size="3" value="6" class="in"></div>
   </div>
   </form>
    </div>
    
    
    
    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.2/js/bootstrap.min.js" integrity="sha384-o+RDsa0aLu++PJvFqy8fFScvbHFLtbvScb8AjopnFD+iEQ7wo/CG0xlczd+2O/em" crossorigin="anonymous"></script>
  </body>
</html>