How to Convert JS Password Strength Meter to Swift - swift

Question

I'm trying to convert this javascript password score function to swift, so I can use the same logic on mobile as we do on web. Here is the JS fiddle with the code to test:
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<pass.length; i++) {
letters[pass[i]] = (letters[pass[i]] || 0) + 1;
score += 5.0 / letters[pass[i]];
}
// bonus points for mixing it up
var variations = {
digits: /\d/.test(pass),
lower: /[a-z]/.test(pass),
upper: /[A-Z]/.test(pass),
nonWords: /\W/.test(pass),
}
variationCount = 0;
for (var check in variations) {
variationCount += (variations[check] == true) ? 1 : 0;
}
score += (variationCount - 1) * 10;
return parseInt(score);
}
function checkPassStrength(pass) {
var score = scorePassword(pass);
if (score > 80)
return "Strong";
if (score > 60)
return "Good";
if (score >= 30)
return "Weak";
return "";
}
I'm having an issue in converting this part:
var letters = new Object();
for (var i=0; i<pass.length; i++) {
letters[pass[i]] = (letters[pass[i]] || 0) + 1;
score += 5.0 / letters[pass[i]];
}
I've tried to create a dictionary to store the character as key and then increment the value with each occurrences of that key, but it's not working as expected.
let string = "Testing22!"
var score = 0
var dictionary = [String.Element: Int]()
for x in string {
let value = dictionary[x] ?? 0
dictionary[x] = value + 1
score += 5 / value
}
print(dictionary) //["s": 1, "T": 1, "g": 1, "2": 2, "n": 1, "i": 1, "!": 1, "t": 1, "e": 1]
print(score)
I'm also not sure of the most efficient way to handle the regex checks for the bonus points section.

Answer 1

I'd port it over to swift like this, I'm sure there are some improvements to be made, but thats a quick conversion:
func scorePassword(_ inputString: String?) -> Double {
var score: Double = 0
guard let string = inputString, !string.isEmpty else { return score }
// award every unique letter until 5 repetitions
let countedSet = NSCountedSet()
for x in string {
countedSet.add(x)
score += 5.0 / Double(countedSet.count(for: x))
}
// bonus points for mixing it up
let variations = [
"^(?=.*[0-9]).*$",
"^(?=.*[a-z]).*$",
"^(?=.*[A-Z]).*$",
"^(?=.*\\W).*$"
]
var variationCount: Double = 0
for check in variations {
print(string.testRegex(check))
variationCount += string.testRegex(check) ? 1 : 0
}
score += (variationCount - 1) * 10
return floor(score)
}
func checkPassStrength(_ inputString: String?) -> String {
let score = scorePassword(inputString)
if score > 80 {
return "Strong"
} else if score > 60 {
return "Good"
} else if score > 30 {
return "Weak"
}
return ""
}
extension String {
func testRegex(_ regex: String) -> Bool {
let test = NSPredicate(format: "SELF MATCHES %#", regex)
return test.evaluate(with: self)
}
}

Answer 2

You can run js code inside Swift and get the result from it, so you can share code between platforms.
let jsSource = """
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<pass.length; i++) {
letters[pass[i]] = (letters[pass[i]] || 0) + 1;
score += 5.0 / letters[pass[i]];
}
// bonus points for mixing it up
var variations = {
digits: /d/.test(pass),
lower: /[a-z]/.test(pass),
upper: /[A-Z]/.test(pass),
nonWords: /W/.test(pass),
}
variationCount = 0;
for (var check in variations) {
variationCount += (variations[check] == true) ? 1 : 0;
}
score += (variationCount - 1) * 10;
return parseInt(score);
}
function checkPassStrength(pass) {
var score = scorePassword(pass);
if (score > 80)
return "Strong";
if (score > 60)
return "Good";
if (score >= 30)
return "Weak";
return "";
}
"""
let context = JSContext()
context?.evaluateScript(jsSource)
let testFunction = context?.objectForKeyedSubscript("scorePassword")
let result = testFunction?.call(withArguments: ["1234"])
print("js result : " , result )
Note; I edited the part "digits: /\d/.test(pass)" to "digits: /d/.test(pass)"