Question

如果我有一个带有多个调用同一功能的键的对象，并且此功能在其范围之外实现，那么如何确定哪个键调用了此功能？例如：

function tellYourAge() {
   return function()
   {
       // I already know here that this refers to Population
       // For example, console.log(this) will print the Population object
   }
}

{
   let Population = {
     Mahdi: tellYourAge(),
     Samuel: tellYourAge(),
     Jon: tellYourAge()
   };

   Population.Mahdi(); // It should log 18
   Population.Samuel(); // It should log 20
   Population.Jon(); // It should log 21
}

Answer 1

可能

function tellYourAge() {
   return function()
   {
       var f = arguments.callee;
       var key = Object.keys(this).filter(key => this[key] === f)[0];
       console.log(key);
   }
}

{
   let Population = {
     Mahdi: tellYourAge(),
     Samuel: tellYourAge(),
     Jon: tellYourAge()
   };

   Population.Mahdi(); // prints Mahdi
   Population.Samuel(); // prints Samuel
   Population.Jon(); // prints Jon
}

说明：arguments.callee引用arguments对象所属的功能。并且this基本上是函数调用时的“点之前的东西”，因此是Population对象。现在，您要做的就是在对象中查找被调用的函数实例，然后完成操作。

Answer 2

function tellYourAge() {
   return function()
   {
      var s = new Error().stack;
      if(s.includes('Mahdi')){
        console.log('Age is 18');
      }

      else if(s.includes('Samuel')){
        console.log('Age is 20');
      }

      else if(s.includes('Jon')){
        console.log('Age is 21');
      } 
   }
}

{
   let Population = {
     Mahdi: tellYourAge(),
     Samuel: tellYourAge(),
     Jon: tellYourAge()
   };

   Population.Mahdi(); // It should log 18
   Population.Samuel(); // It should log 20
   Population.Jon(); // It should log 21
}

Output:
Age is 18
Age is 20
Age is 21

仅供参考，新的Error（）。stack将为您提供如下的堆栈跟踪信息，

Error
    at Object.Samuel (<anonymous>:4:20)
    at <anonymous>:1:19

Answer 3

我理解您的问题是如何将一个人的年龄与其姓名相关联。我要做的方法是创建描述人的对象。每个对象将具有两个属性，即名称和年龄。

然后，将这些对象（人）存储在一个数组中，该数组即人口。

// Create a constructor function which defines a Person
function Person(name, age) {
  this.name = name;
  this.age = age;
}

// Create an array of Population to store the Persons (people)
var Population = [];
Population.push(new Person('Mahdi', 18));
Population.push(new Person('Samuel', 20));
Population.push(new Person('John', 21));

// Counter and limit variables
var i, l;

// Loop through the Population and display the information about the people
l = Population.length;
for (i = 0; i < l; i++) {
  let person = Population[i];
  console.log(person.name + " is " + person.age);
}

Answer 4

您尚未说明为什么您不想“传递参数”，或者确切地不传递参数的要求是什么。我的猜测是，您希望在特定情况下使返回的整数（或其他值）保持动态。

这是我可能会建议这样做的方式，尽管尚不清楚这是否是一个好主意：

function tellYourAge() {
  return function(name)
  {
    let ages = {
      Mahdi: 18,
      Samuel: 20,
      Jon: 21,
    };
    return ages[name];
  }
}

{
  let makePopulation = function(names){
    let pop = {};
    names.forEach(function(n){
      pop[n] = tellYourAge().bind(pop, n);
    });
    return pop;
  };

  let Population = makePopulation("Mahdi", "Samuel", "Jon");

  Population.Mahdi(); // It should log 18
  Population.Samuel(); // It should log 20
  Population.Jon(); // It should log 21
}

如何分辨javascript中哪个键称为函数

4 个答案: