Ascii Sumator JS Fundamentals

function asciiSumator(input) {
    let firstChar = input.shift();
    let secondChar = input.shift();
    let str = input.shift();
    let start = Math.min(firstChar.charCodeAt(0), secondChar.charCodeAt(0));
    let end = Math.max(firstChar.charCodeAt(0), secondChar.charCodeAt(0));
    let sum = 0;
    for (let i = 0; i < str.length; i++) {
      let charCode = str.charCodeAt(i);
      if (charCode > start && charCode < end) {
        sum += charCode;
      }
    }
    console.log(sum);
  }