Question

如何调用此函数内的函数？

var video = function() {

    this.name = "Name of Video";
    this.desc = "Short Description of Video";
    this.long = "Long Description of Video";

    function metadata(){
        return {
            name : this.name,
            shortDescription : this.desc,
            longDescription : this.long
        };
    };

};

Answer 1

使它成为新对象的方法：

var video = function() {

    this.name = "Name of Video";
    this.desc = "Short Description of Video";
    this.long = "Long Description of Video";

    this.metadata = function(){
        return {
            name : this.name,
            shortDescription : this.desc,
            longDescription : this.long
        };
    };
};

var videoObject = new video();
videoObject.metadata();

Answer 2

除了所述功能之外，你不能。

var video = function() {

    this.name = "Name of Video";
    this.desc = "Short Description of Video";
    this.long = "Long Description of Video";

    function metadata(){
        return {
            name : this.name,
            shortDescription : this.desc,
            longDescription : this.long
        };
    };
    metadata();

};

Answer 3

的 jsFiddle Demo 的

有几种选择。一种高度使用的方法是原型。如果使用new关键字，原型将扩展使用原型上定义的函数创建的对象。您可以利用它来公开函数。

var video = function() { if( !(this instanceof video) ){//ensure that we always work with an instance of video return new video(); } this.name = "Name of Video"; this.desc = "Short Description of Video"; this.long = "Long Description of Video"; }; video.prototype.metadata = function(){ return { name : this.name, shortDescription : this.desc, longDescription : this.long }; };

现在选项，可以直接调用：

console.log(video().metadata());

它可以用作函数调用，然后引用

var v = video(); console.log(v.metadata());

或者可以显式实例化然后引用

var vid = new video(); console.log(vid.metadata());

这确保了基本上所有函数的使用最终都具有相同的功能。

Answer 4

您无法直接从第一个外包装功能外部达到嵌套功能：

点击此处了解详情：https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Functions_and_function_scope

因此，一个简单的解决方案是使用附加到返回对象的函数表达式。

var video = function() {

    this.name = "Name of Video";
    this.desc = "Short Description of Video";
    this.long = "Long Description of Video";

    this.metadata = function(){
        return {
            name : this.name,
            shortDescription : this.desc,
            longDescription : this.long
        };
    };
};

new video().metadata();

如何调用函数内的函数？

4 个答案: