https://central.greenroad.com/Scripts/strong-pass.js

1var letters = "abcdefghijklmnopqrstuvwxyz";
2var numbers = "01234567890";
3var symbols = ")!@#$%^&*()";
4var uLetters = letters.toUpperCase();
5
6function getType(char){
7    if(letters.indexOf(char) > -1){
8        return "letter";
9    }
10    if(uLetters.indexOf(char) > -1){
11        return "uLetter";
12    }
13    if(numbers.indexOf(char) > -1){
14        return "number";
15    }
16    //if(symbols.indexOf(char) > -1){
17        return "symbol";
18    //}
19}
20
21function reverseStr(str){
22    var result = "";
23    for(var i = str.length - 1; i > -1; i--){
24        result += str[i];
25    }
26    return result;
27}
28
29function calculateRepeatIncrement(password, index){
30    var len = password.length;
31    var increment = 0;
32    for(var t = 0; t < len; t++){
33        if(index !== t && password[index] === password[t]){
34            increment += len/Math.abs(index - t);
35        }
36    }
37    return increment;
38}
39
40function calculateSequence(password, str){
41    var result = 0;
42    var lPass = password.toLowerCase();
43    var len = str.length - 3;
44
45    for (var i=0; i < len; i++) {
46        var forward = str.substring(i, i + 3);
47        var reverse = reverseStr(forward);
48        if (lPass.indexOf(forward) > -1 || lPass.indexOf(reverse) > -1) {
49            result++;
50        }
51    }
52    return result;
53}
54
55function strongPass(password, config){
56    var score = 0;
57    var len = password.length;
58    var minLength = config && config.minLength || 8;
59
60    var numULetter = 0,
61        numLLetter = 0,
62        numNumber = 0,
63        numSymbol = 0,
64        numMiddle = 0,
65        lastULetter = -1,
66        lastLLetter = -1,
67        lastNumber = -1,
68        lastSymbol = -1,
69        numConsecLLetter = 0,
70        numConsecULetter = 0,
71        numConsecNumber = 0,
72        numConsecSymbol = 0,
73        numRepeat = 0,
74        numRepeatChars = 0;
75
76
77    for(var i = 0; i < len; i++){
78        var type = getType(password[i]);
79
80        if(type === 'letter'){
81            if(lastLLetter > -1 && lastLLetter + 1 === i){
82                numConsecLLetter++;
83            }
84            lastLLetter = i;
85            numLLetter++;
86        }
87        if(type === 'uLetter'){
88            if(lastULetter > -1 && lastULetter + 1 === i){
89                numConsecULetter++;
90            }
91            lastULetter = i;
92            numULetter++;
93        }
94        if(type === 'number'){
95            if(lastNumber > -1 && lastNumber + 1 === i){
96                numConsecNumber++;
97            }
98            lastNumber = i;
99            numNumber++;
100        }
101        if(type === 'symbol'){
102            if(lastSymbol > -1 && lastSymbol + 1 === i){
103                numConsecSymbol++;
104            }
105            lastSymbol = i;
106            numSymbol++;
107        }
108        if(i > 0 && i < len - 1 && ['number', 'symbol'].indexOf(type) > -1){
109            numMiddle++;
110        }
111
112        var increment = calculateRepeatIncrement(password, i);
113        if(increment){
114            numRepeat += increment;
115            numRepeatChars++;
116            numRepeat = (len - numRepeatChars) ? Math.ceil(numRepeat/(len - numRepeatChars)) : Math.ceil(numRepeat);
117        }
118    }
119
120    score += password.length * 4;
121
122    if(numULetter > 0 && numULetter < len){
123        score += (len - numULetter) * 2;
124    }
125    if(numLLetter > 0 && numLLetter < len){
126        score += (len - numLLetter) * 2;
127    }
128    if(numNumber > 0 && numNumber < len){
129        score += numNumber * 4;
130    }
131
132    score += numSymbol * 6;
133    score += numMiddle * 2;
134
135    if(numULetter + numLLetter > 0 && numNumber + numSymbol === 0){
136        score -= len;
137    }
138
139    if(numNumber === len){
140        score -= len;
141    }
142
143    score -= numRepeat;
144
145    score -= numConsecULetter * 2;
146    score -= numConsecLLetter * 2;
147    score -= numConsecNumber * 2;
148
149    score -= calculateSequence(password, letters) * 3;
150    score -= calculateSequence(password, numbers) * 3;
151    score -= calculateSequence(password, symbols) * 3;
152
153    if(len > minLength){
154        var requirements = numLLetter ? 1 : 0;
155        requirements += numULetter ? 1 : 0;
156        requirements += numNumber ? 1 : 0;
157        requirements += numSymbol ? 1 : 0;
158
159        if(requirements > 2){

160            score += requirements * 2 + 2;
161        }
162    }
163
164    if(score < 0){
165        score = 0;
166    } else if(score > 100){
167        score = 100;
168    }
169
170
171    return score;
172}
173
174function toNumber(password, options){
175    var number = strongPass(password, options);
176    if(number === 100){
177        number = 99;
178    }
179    return Math.floor((number + 20)/20);
180}
181
182function toMark(password, options){
183    var number = toNumber(password, options);
184    if(number === 1){
185        return 'Very Weak';
186    }
187    if(number === 2){
188        return 'Weak';
189    }
190    if(number === 3){
191        return 'Good';
192    }
193    if(number === 4){
194        return 'Strong';
195    }
196    if(number === 5){
197        return 'Very Strong';
198    }
199}
200
201toNumber.engine = strongPass;
202toNumber.toMark = toMark;