Printer Errors.js

// In a factory a printer prints labels for boxes. For one kind of boxes the printer has to use colors which, for the sake of simplicity, are named with letters from a to m.
//
//     The colors used by the printer are recorded in a control string. For example a "good" control string would be aaabbbbhaijjjm meaning that the printer used three times color a, four times color b, one time color h then one time color a...
//
// Sometimes there are problems: lack of colors, technical malfunction and a "bad" control string is produced e.g. aaaxbbbbyyhwawiwjjjwwm with letters not from a to m.
//
//     You have to write a function printer_error which given a string will return the error rate of the printer as a string representing a rational whose numerator is the number of errors and the denominator the length of the control string. Don't reduce this fraction to a simpler expression.
//
// The string has a length greater or equal to one and contains only letters from ato z.
//
//     Examples:
// s="aaabbbbhaijjjm"
// printer_error(s) => "0/14"
//
// s="aaaxbbbbyyhwawiwjjjwwm"
// printer_error(s) => "8/22"

function printerError(s) {
    let arr = s.split('')
    let finish = 'm'
    let stopper = finish.charCodeAt(0);
    let counter = 0;
    let res = 0;
    for(let i = 0; i < arr.length; i++) {
        if (arr[i].charCodeAt(0) > stopper) {
            res += 1;
            counter += 1
        }
        else {
            counter += 1
        }

    }
    return `${res}/${counter}`
}