关于javascript:使用-JS-实现简易计算器

要求：应用 js 实现繁难计算器，可计算蕴含 +、-、*、/及 () 的字符串表达式
实现：

const highPriorityRegex = /(?<n1>\d+)\s*?(?<operator>\*|\/)\s*?(?<n2>\d+)/
const lowPriorityRegex = /(?<n1>\d+)\s*?(?<operator>\+|\-)\s*?(?<n2>\d+)/

function calc(str: string) {
  // 先查找左侧括号
  const lI = [...str].findIndex(c => c === '(');

  if (lI > -1) {
    // 找寻对应的右侧括号
    const rI = [...str].findLastIndex(c => c === ')');
    // 将括号内的内容通过递归的模式失去后果后，在替换回去
    str = str.slice(0, lI) + calc(str.slice(lI + 1, rI)) + str.slice(rI + 1)
  }

  let matches;

  // 先匹配乘除
  while ((matches = str.match(highPriorityRegex))) {const { 0: { length}, groups, index } = matches;
    const {n1, n2, operator} = groups!

    const res = operator === '*' ? (+n1 * +n2) : (+n1 / +n2)

    str = str.slice(0, index!) + `${res}` + str.slice(index! + length)
  }

  // 再解决加减
  while ((matches = str.match(lowPriorityRegex))) {const { 0: { length}, groups, index } = matches;
    const {n1, n2, operator} = groups!

    const res = operator === '+' ? (+n1 + +n2) : (+n1 - +n2)

    str = str.slice(0, index!) + `${res}` + str.slice(index! + length)
  }

  return +str
}