printerErrors.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 numerator = 0; // Count of errors
  let denominator = s.length; // Total characters
  
  for (let i = 0; i < s.length; i++) {
    if (s[i] < 'a' || s[i] > 'm') { // Check if character is out of range
      numerator++;
    }
  }
  
  return `${numerator}/${denominator}`; // Return fraction as a string
}


//or:
// function printerError(s) {
//   let numerator = s.match(/[^a-m]/g)?.length || 0;
//   let denominator = s.length;
//   return `${numerator}/${denominator}`;
// }