I am doing exercises in javascript and i came across a problem. the user should choose the character length in the password however if i select 4 characters in the input I get 3. why?
my thought was to be useful to choose the number of characters and to generate a password as many characters as there are. where I am wrong I ask for help!
function generirajLozinku(pLength) {
var keyListAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
keyListInt = "123456789",
keyListSpec = "",
password = '@';
var len = Math.ceil(pLength / 2); // mijenanjem ovog broja mijenja se duzina lozinke
len = len - 1;
var lenSpec = pLength - 2 * len;
for (i = 0; i < len; i++) {
password += keyListAlpha.charAt(Math.floor(Math.random() * keyListAlpha.length));
password += keyListInt.charAt(Math.floor(Math.random() * keyListInt.length));
}
for (i = 0; i < lenSpec; i++)
password += keyListSpec.charAt(Math.floor(Math.random() * keyListSpec.length));
password = password.split('').sort(function() {
return 0.5 - Math.random()
}).join('');
return password;
}
function myFunction() {
var x = document.getElementById("num").value;
document.getElementById("demo2").innerText = generirajLozinku(x);
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Document</title>
</head>
<body>
<section>
<div>
<h1>Your strong password marker</h1>
<p>Password length</p>
<input type="number" name="izaberi boj karaktera!" id="num" min="4" max="10">
<br>
<button onclick="myFunction()">Generate</button>
<p id="demo2">Your password</p>
</div>
<div>
</div>
</section>
</body>
</html>The reason for your code not working is this is the last loop where you try to fill up the missing characters:
for (i = 0; i < lenSpec; i++)
password += keyListSpec.charAt(Math.floor(Math.random() * keyListSpec.length));
You choose a random character from keyListSpec, but you defined keyListSpec as keyListSpec = "", so there is nothing to choose from.
The design choice of your code is really strange. The passwords generated have a very predictable pattern, which will dramatically reduce possible combinations. The suffering of the characters in the password does not help there. In addition to that the sort(function() { return 0.5 - Math.random() }) is not a very good way of shuffling.
Also Math.random() is not a good choice when it comes to password generation. If you are looking for a password generator written in JavaScript you should take a look at e.g. Generate random password string with requirements in javascript in particular at this answer.
It was not working for evens it seems, ie 4, 6, etc. The way you handled odds vs evens looked off. I did a simpler version for you.
function generirajLozinku(pLength) {
var keyListAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789",
password = '@';
var len = pLength - 1;
for (i = 0; i < len; i++) {
password += keyListAlpha.charAt(Math.floor(Math.random() * keyListAlpha.length));
}
password = password.split('').sort(function() {
return 0.5 - Math.random()
}).join('');
return password;
}
function myFunction() {
var x = document.getElementById("num").value;
document.getElementById("demo2").innerText = generirajLozinku(x);
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Document</title>
</head>
<body>
<section>
<div>
<h1>Your strong password marker</h1>
<p>Password length</p>
<input type="number" name="izaberi boj karaktera!" id="num" min="4" max="10">
<br>
<button onclick="myFunction()">Generate</button>
<p id="demo2">Your password</p>
</div>
<div>
</div>
</section>
</body>
</html>Check your code and comment it. pLength = 4 because keyListSpec = "" so the follwing code
// keyListSpec is "", so keyListSpec.charAt always return ""
for (let i = 0; i < lenSpec; i++)
password += keyListSpec.charAt(Math.floor(Math.random() * keyListSpec.length));
function generirajLozinku(pLength) {
var keyListAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
keyListInt = "123456789",
keyListSpec = "",
password = '@';
var len = Math.ceil(pLength / 2); // mijenanjem ovog broja mijenja se duzina lozinke
len = len - 1;
var lenSpec = pLength - 2 * len;
// if pLength = 4 , len is 1 and lenSpec is 2
// here password is "@"
for (let i = 0; i < len; i++) {
password += keyListAlpha.charAt(Math.floor(Math.random() * keyListAlpha.length));
password += keyListInt.charAt(Math.floor(Math.random() * keyListInt.length));
}
// if pLength = 4 , len is 1 and lenSpec is 2
// here password length is 3 "@xx"
console.log("keyListSpec", keyListSpec);
// keyListSpec is "", so keyListSpec.charAt always return ""
for (let i = 0; i < lenSpec; i++)
password += keyListSpec.charAt(Math.floor(Math.random() * keyListSpec.length));
password = password.split('').sort(function() {
return 0.5 - Math.random()
}).join('');
return password;
}