let Computer = function () {
        this.computerValue  = http://www.mamicode.com/‘computerValue‘;
    };
    Computer.prototype.fun = function () {
        console.log(‘calculate‘);
    };
    let mac = new Computer();
    mac.fun = 1;
    let acer = new Computer();
    console.log(acer.fun); //为什么acer的fun不是1