Simple calculator

function calculator(stringCalculation) {
  let numbers = []
  let operators = []
  let currentDigits = ''

  for (let i = 0; i < stringCalculation.length + 1; i++) {
    const currentSymbol = stringCalculation[i]
    const number = parseInt(currentSymbol)

    if (Number.isNaN(number)) {
      numbers.push(parseInt(currentDigits))

      if (currentSymbol) {
        operators.push(currentSymbol)
      }

      currentDigits = ''
    } else {
      currentDigits += number
    }
  }

  return calculate(numbers, operators)
}

function action(arg1, arg2, operator) {
  switch (operator) {
    case "+":
      return arg1 + arg2;
    case "*":
      return arg1 * arg2;
  }

  return 0
}

const symbolPriority = ['*', ':', '+', '-']

function calculate(numbers, operators) {
  if (operators.length === 0) {
    return numbers[0] ?? 0
  }

  let index = -1
  for (let i = 0; i < symbolPriority.length; i++) {
    index = operators.indexOf(symbolPriority[i])
    if (index !== -1) {
      break;
    }
  }

  const firstPart = numbers.slice(0, index)
  const secondPart = numbers.slice(index + 2)
  const localResult = action(numbers[index], numbers[index + 1], operators[index])

  const newNumbers = [...firstPart, localResult, ...secondPart]
  const newOperators = operators.filter((_, idx) => idx !== index)

  return calculate(newNumbers, newOperators)
}

calculator("11+2*3+4")