Question

我试图完全掌握JavaScript inheritance 和 encapsulation 。采用以下示例（ and here is a fiddle of it ）：

myPage = {
    someObj: function() {
        var x = 0;        

        //PRIVATE: increment by 10
        var inc10 = function() {
            x = x+10;
        };

        //PUBLIC: increment
        this.inc = function() {
            x = x+1;
        };

        //PUBLIC: decrement
        this.dec = function() {
            x = x-1;
        };

        //PUBLIC: output the current value of x
        this.getValue = function() {
            return x;
        }

        inc10(); //as soon as obj1 is created lets add 10
        this.inc(); //as soon as obj1 is created lets add 1 more
    }
};

obj1 = new myPage.someObj(); //x starts out at 11
// obj1.inc10(); won't work because it's private, excellent
obj1.dec();
obj1.inc();

alert(obj1.getValue());

我的问题是关于inc()方法。我需要它可以从对象的内部和外部调用。这是正确的方法吗？

Answer 1

我需要它可以从对象的内部和外部调用。这是正确的方法吗？

您的脚本似乎已按预期工作，您在构造函数中将方法调用为this.inc()非常正确 - 不确定为什么需要改进。

然而，您可以将其定义为本地函数，然后将其作为方法导出 - 并使其仍然可用＆＃34;内部＆＃34;作为局部变量：

function SomeObj() {
    // local declarations:
    var x;
    function inc10() {
        x = x+10;
    }
    function inc1() {
        x = x+1;
    }

    // exported as property:
    this.inc = inc1; // <== the function from above, not a literal
    this.dec = function() {
        x = x-1;
    };
    this.getValue = function() {
        return x;
    };

    // initialisation:
    x = 0;
    inc10();
    inc1(); // this.inc() would still work
}

Answer 2

从内部和外部调用函数而不将其附加到对象。

这应该有用......

myPage = function() {

        var x = 0;        

        //PRIVATE: increment by 10
        var inc10 = function() {
            x = x+10;
        };

        //PUBLIC: increment
        this.inc = function() {
            x = x+1;
        };

        //PUBLIC: decrement
        this.dec = function() {
            x = x-1;
        };

        //PUBLIC: output the current value of x
        this.getValue = function() {
            return x;
        }

        inc10(); //as soon as obj1 is created lets add 10
        this.inc(); //as soon as obj1 is created lets add 1 more

};

obj1 = new myPage; //x starts out at 11
// obj1.inc10(); won't work because it's private, excellent
obj1.inc();

alert(obj1.getValue());

如何定义需要从obj和out内部访问的javascript内部方法

2 个答案: