Javascript recursive function to do math calculation on string formula input

mathCalculation.js

// recursive function to do math calculation on string formula input
// use case: mathCalculation("1 * 2 + 4 / 2 - 6")

function mathCalculation (formula) {
  const plusOperator = '+'
  const minusOperator = '-'
  const multiplyOperator = '*'
  const divideOperator = '/'

  if (formula.indexOf(plusOperator) > 0) {
    const operands = formula.split(plusOperator)
    let total = 0

    operands.forEach(operand => {
      total = total + mathCalculation(operand)
    })

    return total
  }

  else if (formula.indexOf(minusOperator) > 0) {
    const operands = formula.split(minusOperator)
    let total = 0

    operands.forEach((operand, index) => {
      if (index === 0) {
        total = mathCalculation(operand)
      } 
      else {
        total = total - mathCalculation(operand)
      }
    })

    return total
  }

  else if (formula.indexOf(multiplyOperator) > 0) {
    const operands = formula.split(multiplyOperator)
    let total = 1

    operands.forEach(operand => {
      total = total * mathCalculation(operand)
    })

    return total
  }

  else if (formula.indexOf(divideOperator) > 0) {
    const operands = formula.split(divideOperator)
    let total = 1

    operands.forEach((operand, index) => {
      if (index === 0) {
        total = mathCalculation(operand)
      }
      else {
        total = total / mathCalculation(operand)
      }
    })

    return total
  }

  return Number(formula)
}