Count appearance of each character

Question

I'm currently working on a password strength calculator and then I need to know if a character appears more than once.
I know I must use regex like this occurance = password.match(/a/g).length to get ho many times a occurs, but I want to do that with each character (letter, number, symbol).

Is there a way to do that using JS / JQuery, maybe regex, other than working with an array which contains all characters I want to test ?

Answer 1

Something like this?

var hello = "Hello world";
var histogram = {};

for (var i = 0, len = hello.length; i < len; i++) {
    var letter = hello[i];
    histogram[letter] = (histogram[letter] || 0) + 1;
}

console.log(histogram);

Result:

{ H: 1, e: 1, l: 3, o: 2, ' ': 1, w: 1, r: 1, d: 1 }

Or you may use array. Just change {} to [].