JavaScript Password Generator with Rules

This JavaScript code snippet helps you to create a user-friendly password generator. It lets you customize password length and criteria (lowercase, uppercase, numbers, symbols) for secure and tailored password generation. The core function is to generate and display passwords based on user-defined rules. It’s a handy tool for quickly generating strong passwords.

It’s helpful for user registration or password reset forms, ensuring users create robust and unique passwords.

How to Create a Password Generator with Rules using JavaScript

1. Start by creating the HTML structure for your password generator. You can place this code inside your HTML file.

<div id="password-generator">

    <input value="Password generator" id="password-output">

    <div class="range">
      <input 
        type="range"
        min="4"
        max="24"
        step="1"
        value="8"
        id="password-length"
        oninput="document.getElementById('display-password-length').value=this.value"
      >
      <input 
        type="text"
        value="8"
        maxlength="2"
        id="display-password-length"
        oninput="document.getElementById('password-length').value=this.value"
      >
    </div>

    <div class="flex">
      <input type="checkbox" id="lowercase" checked="checked">
      <label for="lowercase">a-z</label>

      <input type="checkbox" id="uppercase">
      <label for="uppercase">A-Z</label>

      <input type="checkbox" id="numbers">
      <label for="numbers">0-9</label>

      <input type="checkbox" id="symbols">
      <label for="symbols">!-?</label>
    </div>

    <button id="generateButton" type="button" onclick="generatePassword()">Generate</button>

  </div>

2. Use the following CSS code to style your password generator. This CSS code ensures a visually appealing and user-friendly interface.

@import url("https://fonts.googleapis.com/css?family=Cuprum&display=swap");
* {
  box-sizing: border-box;
  font-family: "Cuprum", sans-serif;
}

input {
  border: none;
  background: transparent;
  outline: none;
}

body {
  overflow: hidden;
  margin: 0;
  padding: 0;
  display: flex;
  align-items: center;
  text-align: center;
  height: 100vh;
  background: #F44336;
}
body #password-generator {
  padding: 2rem;
  margin: 0 auto;
  width: 500px;
  border-radius: 3px;
  box-shadow: 0 0 2px #1f1f1f;
  border: 3px solid #d5d4ff;
  position: relative;
  white-space: nowrap;
}
body #password-generator #password-output {
  text-align: center;
  font-size: 2.5rem;
  margin: 0 auto 1.2rem;
  width: 100%;
}
body #password-generator .range {
  justify-content: space-between;
  padding: 1rem 1rem 1rem 2.5rem;
}
body #password-generator .range input[type=range] {
  -webkit-appearance: none;
  appearance: none;
  width: 40%;
  max-width: 100%;
  height: 15px;
  padding: 0px;
  background: #d5d4ff;
  outline: none;
  opacity: 0.7;
  -webkit-transition: 0.2s;
  transition: opacity 0.2s;
  box-shadow: 0 2px 35px rgba(0, 0, 0, 0.4555);
  border-radius: 10px;
  cursor: pointer;
  scroll-behavior: smooth;
  z-index: 1;
}
body #password-generator .range input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 15px;
  height: 15px;
  background: black;
  cursor: pointer;
  border-radius: 18px;
  transition: 0.5s ease;
}
body #password-generator .range input[type=range]::-webkit-slider-thumb:focus, body #password-generator .range input[type=range]::-webkit-slider-thumb:active {
  padding: 16px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.25);
}
body #password-generator .range #display-password-length {
  text-align: center;
  font-size: 1.4rem;
  width: 80px;
  padding-top: 10px;
}
body #password-generator .flex {
  margin: 1rem 1rem 2rem;
  display: flex;
  justify-content: space-between;
}
body #password-generator .flex input {
  display: none;
}
body #password-generator .flex input:checked + label {
  background: #d5d4ff;
  filter: brightness(120%);
  transform: scale(1.1);
}
body #password-generator .flex label {
  border: 2px solid #d5d4ff;
  border-radius: 4px;
  padding: 0.8rem;
  cursor: pointer;
  font-size: 1.3rem;
  text-align: center;
  display: block;
  width: 80px;
  transition: 0.2s ease;
}
body #password-generator .flex label:hover {
  filter: sepia(70%);
}
body #password-generator button {
  outline: none;
  background: #d5d4ff;
  border: none;
  padding: 1rem 2rem;
  margin: 0.5rem 0;
  border-radius: 3px;
  box-shadow: 1px 1px 3px #1f1f1f;
  text-transform: uppercase;
  font-size: 1.2rem;
  transition: 0.2s ease;
  cursor: pointer;
}
body #password-generator button:hover {
  transform: translateX(4px);
  filter: brightness(120%);
}

3. Finally, add the JavaScript logic to make the password generator functional. This code defines the password criteria and generates the password accordingly.

const passwordOutput =  document.getElementById('password-output');
const dataLowercase = "azertyuiopqsdfghjklmwxcvbn".split('');
const dataUppercase = "AZERTYUIOPQSDFGHJKLMWXCVBN".split('');
const dataNumbers = "0123456789".split('');
const dataSymbols = "!@#$%^&*-_=+\|:;',.>/?~".split('');

function generatePassword() {

  const data = [].concat(
    lowercase.checked ? dataLowercase : [],
    uppercase.checked ? dataUppercase : [],
    numbers.checked ? dataNumbers : [],
    symbols.checked ? dataSymbols : []
  );

  let passwordLength = parseInt(document.getElementById('display-password-length').value);
  let newPassword = '';

  if (data.length === 0) {
    passwordOutput.innerHTML = "Générateur de MDP";
    alert('Please check at least one criteria');
    return;
  }

  for (let i = 0; i < passwordLength; i++) {
    newPassword += data[Math.floor(Math.random() * data.length)];
  }
  passwordOutput.value = newPassword;
  
  passwordOutput.select();
  document.execCommand('copy');
  generateButton.innerHTML = "Copied !";
  setTimeout(() => {generateButton.innerHTML = "Générer mot de passe"}, 3500);

}

You can customize this code by adding more criteria or changing the styling to match your website or application’s design. Once you’re satisfied, integrate it into your project, and ensure the “generatePassword()” function is called when the user clicks the “Generate” button.

That’s it! hopefully, you have successfully created a JavaScript Password Generator With Rules. If you have any questions or suggestions, feel free to comment below.

Asif Mughal

I code and create web elements for amazing people around the world. I like work with new people. New people new Experiences.
I truly enjoy what I’m doing, which makes me more passionate about web development and coding. I am always ready to do challenging tasks whether it is about creating a custom CMS from scratch or customizing an existing system.