passwordCheck.js

This is a password strength meter in JavaScript, inspired by Steve Moitozo here, but now completely reworked.

Assumptions

We assume a few rules that make a password "stronger":

• We want at least 8 characters
• We want at least one character of each of the following groups:
  • Lowercase letters
  • Uppercase letters
  • Numbers
  • Special characters
• More unique characters are better than less
• Repetitions (like "aa" or "bb" or "1111") are bad
• Sequences (like "12345" or "abc" or "xyz") are bad too

Return value

The function returns a percentage. 100% is the minimally strong password, based on our assumptions. Anything below that is weak, anything above is always stronger.

Usage

passwordCheck("hell0th3re!", function(result) {
	alert(result);
});