今日份关于JS中this问题的小练习来了，大家一起来讨论呀！

第一题

    obj = {
        x: 5
    };
obj.fn = (function () {
    this.x *= ++x;
    return function (y) {
        this.x *= (++x) + y;
        console.log(x);
    }
})();
var fn = obj.fn;
obj.fn(6);//13
fn(4); //234
console.log(obj.x, x, window.x); //95 234 234

第二题

let obj = {
    fn: (function () {
        return function () {
            console.log(this);
        }
    })()
};
obj.fn();
let fn = obj.fn;
fn(); 

第三题

var fullName = 'language';
var obj = {
    fullName: 'javascript',
    prop: {
        getFullName: function () {
            return this.fullName;
        }
    }
};
console.log(obj.prop.getFullName());
var test = obj.prop.getFullName;
console.log(test()); 

第四题

var name = 'window';
var Tom = {
    name: "Tom",
    show: function () {
        console.log(this.name);
    },
    wait: function () {
        var fun = this.show;
        fun();
    }
};
Tom.wait(); 

第五题

window.val = 1;
var json = {
    val: 10,
    dbl: function () {
        this.val *= 2;
    }
}
json.dbl();
var dbl = json.dbl;
dbl();
json.dbl.call(window);
alert(window.val + json.val); 

第六题

(function () {
    var val = 1;
    var json = {
        val: 10,
        dbl: function () {
            val *= 2;
        }
    };
    json.dbl();
    alert(json.val + val);
})();