new Vue({
   el: "#app",
   data: {
    equation: '0',
    isDecimalAdded: false, //防止在一组数字中间输入超过一个小数位
    isOperatorAdded: false, //判断之否已点击 加、减、乘、除，防止连续点击超过一个运算符号
    isStarted: false, //判断计算器是否已经开始输入数字，用于正负数和百分比计算的时候作一些判断
   },
   methods: {
    //Check if the character is + - × ÷
    isOperator(character) { //用来判断character 是否加减乘除
     return ['+', '-', '×', '÷'].indexOf(character) > -1
    },
    append(character) { //append(character)加减乘除
     if (this.equation === '0' && !this.isOperator(character)) {
      if (character === '.') {
       this.equation += '' + character
       this.isDecimalAdded = true
      } else {
       this.equation = '' + character
      }
      this.isStarted = true
      return
     }

     if (!this.isOperator(character)) {
      if (character === '.' && this.isDecimalAdded) {
       return
      }

      if (character === '.') {
       this.isDecimalAdded = true
       this.isOperatorAdded = true
      } else {
       this.isOperatorAdded = false
      }
      this.equation += '' + character
     }

     if (this.isOperator(character) && !this.isOperatorAdded) {
      this.equation += '' + character
      this.isDecimalAdded = false
      this.isOperatorAdded = true
     }
    },
    calculate() { //等于号的时候
     let result = this.equation.replace(new RegExp('×', 'g'), '*').replace(new RegExp('÷', 'g'), '/')
     this.equation = parseFloat(eval(result).toFixed(9)).toString()
     this.isDecimalAdded = false
     this.isOperatorAdded = false
    },
    calculateToggle() { //点击正负号
     if (this.isOperatorAdded || !this.isStarted) {
      true
     }

     this.equation = this.equation + '* -1'
     this.calculate()
    },
    calculatePercentage() { //点击百分比
     if (this.isOperatorAdded || !this.isStarted) {
      true
     }

     this.equation = this.equation + '* 0.01'
     this.calculate()
    },
    clear() { //点击AC
     this.equation = '0'
     this.isDecimalAdded = false //防止在一组数字中间输入超过一个小数位
     this.isOperatorAdded = false //判断之否已点击 加、减、乘、除，防止连续点击超过一个运算符号
     this.isStarted = false //判断计算器是否已经开始输入数字，用于正负数和百分比计算的时候作一些判断
    }
   }
})