Update: created a js fiddle here to see it live: http://jsfiddle.net/HFMvX/
I went through tons of google searches and didn't find anything satisfying. i like how passpack have done it so essentially reverse-engineered their approach, here we go:
function scorePassword(pass) {
var score = 0;
if (!pass)
return score;
// award every unique letter until 5 repetitions
var letters = new Object();
for (var i=0; i
Good passwords start to score around 60 or so, here's function to translate that in words:
function checkPassStrength(pass) {
var score = scorePassword(pass);
if (score > 80)
return "strong";
if (score > 60)
return "good";
if (score >= 30)
return "weak";
return "";
}
you might want to tune this a bit but i found it working for me nicely