11.简易计算器methods核心业务代码

eval("this.result=parseFloat(this.n1)${this.opt}parseFloat(this.n2)")

要么就用switch

switch(this.opt){
    case "+":
        this.result=parseFloat(this.n1)+parseFloat(this.n2)
        break;    
    case "-":
        this.result=parseFloat(this.n1)-parseFloat(this.n2)
        break;
    case "*":
        this.result=parseFloat(this.n1)*parseFloat(this.n2)
        break;
    case "/":
        this.result=parseFloat(this.n1)/parseFloat(this.n2)
        break;
}