Add Operators

operators.js

const add = (nums) => {
  const allNums = nums.toString().split("").map((num) => parseInt(num));
  return allNums.reduce((acc, cur) => acc + cur, 0);
};

const multiply = (nums) => {
  const allNums = nums.toString().split("").map((num) => parseInt(num));
  return allNums.reduce((acc, cur) => acc * cur, 1);
};

const stringify = (number, sign) => {
  const numberStrings = number.toString();
  let str = "";
  for (let i = 0; i < numberStrings.length; i++) {
    if (i === numberStrings.length - 1) {
      str = str + numberStrings[i];
    } else {
      str = str + numberStrings[i] + sign;
    }
  }
  return str;
};

const addOperators = (source, target) => {
  let possible = [];
  const addition = add(source);
  const product = multiply(source);

  if (addition === target) {
    possible.push(stringify(source, "+"));
  }

  if (product === target) {
    possible.push(stringify(source, "*"));
  }

  return possible;
};

addOperators(123, 6); // ["1+2+3", "1*2*3"]
addOperators(1234, 24); // ["1*2*3*4"]
addOperators(3456237490, 9191); // []