如何使用ES6訪問返回對象（模塊模式）中的「公共」函數？

Question

在ES5中使用模塊模式時，調用this.methodName會給我返回對象中的methodName。但在ES6它現在有一點點不同....

舊的方式（與ES5）：

var moduleOld = (function() { 
    //private 
    var privateArray = [1,2,3,4]; 

    return { 
     getItemCount: function() { 
     return privateArray.length; 
     }, 

     getTotal: function() { 
     return this.getItemCount(); 
     } 
    }; 
    })(); 

    //output 
    console.log(moduleOld.getTotal()); //4 <-- Now, I want the same results with ES6 syntax 

新的方式（用ES6）：

let moduleES6 = (()=> { 
    //private 
    let privateArray = [1,2,3,4]; 

    return { 
     getItemCount:()=> { 
     return privateArray.length; 
     }, 

     getTotal:()=> { 
     return this.getItemCount(); 
     } 
    }; 
    })(); 

    //output 
    console.log("es6 ", moduleES6.getTotal()); //Uncaught TypeError: this.getItemCount is not a function 

有辦法它周圍...

let moduleES6_2 = (()=> { 
    //private 
    let privateArray = [1,2,3,4]; 

    return { 
     getItemCount:()=> { 
     return privateArray.length; 
     }, 

     getTotal:()=> { 
     return moduleES6_2.getItemCount(); // I changed "this" to the module name, i.e. moduleES6_2 
     } 
    }; 
    })(); 

    //output 
    console.log("es6 calling by module name: ", moduleES6_2.getTotal()); //works! But what if I change the module's name? Then I have to also change the function call in the getTotal function. 

這種方式，改變模塊的名稱應該不是太大的問題：

let moduleES6_3 = (()=> { 
    //private 
    let privateArray = [1,2,3,4]; 
    function getItemCount() { 
     return privateArray.length; 
    } 
    return { 
     //getItemCount: getItemCount, 
     getTotal:()=> { 
     return getItemCount(); // I am calling the private method. Not the public method! 
     } 
    }; 
    })(); 

    //output 
    console.log("es6 by private method: ", moduleES6_3.getTotal()); //works! But I don't really use the method in the return object, but rather the private declared method. 

如何使用ES6訪問返回對象（模塊模式）中的「公共」函數？

let moduleES6 = (()=> { 
    //private 
    let privateArray = [1,2,3,4]; 
    function getItemCount() { 
     return privateArray.length; 
    } 
    return { 
     getItemCount:()=> { 
     return privateArray.length; 
     }, 
     getTotal:()=> { 
     return this.getItemCount();//<-- how to access the public getItemCount method? 
     } 
    }; 
    })(); 

Answer 1

您可以使用對象方法的語法速記像getItemCount()：

let moduleES6 = (()=> { 
    //private 
    let privateArray = [1,2,3,4]; 

    return { 
    getItemCount() { 
     return privateArray.length; 
    }, 

    getTotal() { 
     return this.getItemCount(); 
    } 
    }; 
})(); 

moduleES6.getTotal() //4