题目：写一个函数，计算 1+2*(3+4*(5+6))
//分割字符串为数组，将数字有运算符分开const _splitNumber = res => { return res.match(/\d+|[^\d\s\t]/g) }// 判断元素是否为数组const _isNumber = res => { return (/^\d+$/).test(res) }// 判断是否为 + - * / 运算符const _isOperator = res => { return (/^[\+\-\*\/#]$/).test(res) }// 判断运算符的级别const _isSymbol = createIsSymbol()// 进行运算const _operator = { '+': (first, last) => { return first + last }, '-': (first, last) => { return first - last }, '*': (first, last) => { return first * last }, '/': (first, last) => { return first / last },}// 计算式子的函数 ---- 采用波兰式function math(number) { let num = _splitNumber(number) return operator(transformation(num));}function transformation(number) { number.push('#') let num = [] let operator = [] number.forEach(item => { if (_isNumber(item)) { // item 为 数字 num.push(item); } else if (_isOperator(item)) { // item 为 运算符 while (operator.length) { const op = operator[operator.length - 1] if (op === "(") { // 上次存入的运算符为 ( break; } else if (_isSymbol(item) > _isSymbol(op)) { // 当前的运算符优先级大于上次存储的那个 break; } else { num.push(operator.pop()) } } operator.push(item) } else { // item 为 ( ) if (item === '(') { // 当前符号为 ( operator.push(item) } else { // 当前符号为 ) while (operator[operator.length - 1] !== '(') { num.push(operator.pop()) } operator.pop() } } }); return num;}function operator(number) { let calcStack = []; number.forEach(item => { if (_isNumber(item)) { calcStack.push(+item) } else { const firstNumber = calcStack.pop(); const lastNumber = calcStack.pop(); calcStack.push(_operator[item](firstNumber, lastNumber)) } }) return calcStack[0];}function createIsSymbol() { let set = { '+': 1, '-': 1, '*': 2, '/': 2, '#': 0 } return function (symbol) { return set[symbol] }}math('1+2*(3+4*(5+6))');console.log( math('1+2*(3+4*(5+6))') );
