javascript password generator

What would be the best approach to creating a 8 character random password containing a-z, A-Z and 0-9?

Absolutely no security issues, this is merely for prototyping, I just want data that looks realistic.

I was thinking a for (0 to 7) Math.random to produce ASCII codes and convert them to characters. Do you have any other suggestions?

I would probably use something like this:

function generatePassword() {
    var length = 8,
        charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
        retVal = "";
    for (var i = 0, n = charset.length; i < length; ++i) {
        retVal += charset.charAt(Math.floor(Math.random() * n));
    }
    return retVal;
}

That can then be extended to have the length and charset passed by a parameter.

This is the quickest and easiest way I know of:

Math.random().toString(36).slice(2)

The idea is to cast a random number (in the range 0..1) to a base36 string (lowercase a-z plus 0-9) and remove the leading zero and decimal point.

Please note that all passwords that is pseudo-generated have some form of vulnerability. However, I would say it is good enough for all normal use-cases. Furthermore, the theoretical length if this password is not guaranteed. It is 16 characters maximum and 0 characters minimum. When run in a loop 1 million times its average length is 15.67 characters with a minimum length of 5. However if you join two of these passwords together, you will get a maximum length of 32 characters, with an average length of 31.33 chars and a minimum length of 20.

Math.random().toString(36).slice(2) + Math.random().toString(36).slice(2)

Personally I use this as a chrome bookmarklet in my browser bookmarks bar to speedily generate passwords:

javascript:(
    function(){
        prompt('Here is your shiny new password:', 
            Math.random().toString(36).slice(2) + 
            Math.random().toString(36).slice(2)
        );
    }
)();

function password_generator( len ) {
    var length = (len)?(len):(10);
    var string = "abcdefghijklmnopqrstuvwxyz"; //to upper 
    var numeric = '0123456789';
    var punctuation = '!@#$%^&*()_+~`|}{[]\:;?><,./-=';
    var password = "";
    var character = "";
    var crunch = true;
    while( password.length<length ) {
        entity1 = Math.ceil(string.length * Math.random()*Math.random());
        entity2 = Math.ceil(numeric.length * Math.random()*Math.random());
        entity3 = Math.ceil(punctuation.length * Math.random()*Math.random());
        hold = string.charAt( entity1 );
        hold = (password.length%2==0)?(hold.toUpperCase()):(hold);
        character += hold;
        character += numeric.charAt( entity2 );
        character += punctuation.charAt( entity3 );
        password = character;
    }
    password=password.split('').sort(function(){return 0.5-Math.random()}).join('');
    return password.substr(0,len);
}

console.log( password_generator() );

This generates a little more robust password that should pass any password strength test. eg: f1&d2?I4(h1&, C1^y1)j1@G2#, j2{h6%b5@R2)

function generatePass(pLength){

    var keyListAlpha="abcdefghijklmnopqrstuvwxyz",
        keyListInt="123456789",
        keyListSpec="!@#_",
        password='';
    var len = Math.ceil(pLength/2);
    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;
}

This is my function for generating a 8-character crypto-random password:

function generatePassword() {
    var buf = new Uint8Array(6);
    window.crypto.getRandomValues(buf);
    return btoa(String.fromCharCode.apply(null, buf));
}

What it does: Retrieves 6 crypto-random 8-bit integers and encodes them with Base64.

Since the result is in the Base64 character set the generated password may consist of A-Z, a-z, 0-9, + and /.

javascript password generator

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