Advanced Password Strength Tester In JavaScript

Category: Form | September 19, 2023
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Last Update:September 19, 2023


Advanced Password Strength Tester In JavaScript


The Password Strength Tester JavaScript library analyzes passwords to determine their relative strength. Works both for browser and Node.js.

It checks for common passwords, calculates entropy bits using Shannon and trigraph methods, and inspects which character sets are used.

How to use it:

1. Download and import the password-strength.js library.

<script src="/lib/password-strength.js"></script>

2. Initialize the PasswordStrength and import lists of common passwords the library uses to cross-reference your password (OPTIONAL).

window.passwordStrength = new PasswordStrength();
$.getJSON("/data/common-passwords.json", function (data) {
$.getJSON("/data/trigraphs.json", function (data) {

3. Test a password like “cssscript” and it returns detailed results including strength code, charset info, entropy bits, and more. This data helps you give helpful strength feedback during signup flows and password creation.

if (window.passwordStrength) {
  strength = window.passwordStrength.check("cssscript");
  if (strength.strengthCode.indexOf('WEAK') >= 0) {
    alert("Your password is too weak.");
// Password Statistics
charsetSize: 63
commonPassword: false
nistEntropyBits: 31.5
passwordLength: 13
shannonEntropyBits: 41.35082883367073
strengthCode: STRONG
trigraphEntropyBits: 75.9034197141653
  number: false
  lower: true
  upper: true
  punctuation: true
  symbol: false

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