Question

我正在尝试调用动态命名对象的方法。

我有一些对象，每个对象包含一个名为“ getWeight”的方法。我需要调用这些对象的子集的此方法。但是，对象的子集取决于用户输入的信息，这就是为什么我试图动态构造对象名称并在循环内调用它的'getWeight'方法的原因。

我的代码如下：

// Importing objects containing 'getWeight' method
const Apple = require('../classses/Apple');
const Pear = require('../classes/Pear);
const Carrot = require('../classes/Carrot);
const Potato = require('../classes/Potato);

const promises = {};
const user = 'userX';  // This is the inputted info, could also equal 'userY'.
const searchableFoods = {
  userX: ['Apple', 'Pear'],
  userY: ['Carrot', 'Potato']
};

for (i = 0; i < searchableFoods[user].length; ++i) {
  promises[searchableFoods[user][i]] = new Promise(function(resolve, reject) {
    // Below line should behave like: Apple.getWeight(arg1, function....
    searchableFoods[user][i].getWeight(arg1, function(response) {
      resolve(response);
    })
  })
}

不幸的是，我收到此错误：

[searchableFoods[user][i].getweight] is not a function

我尝试了多种变体，但无法使其正常工作。可以这样做吗？

Answer 1

可以定义不使用字符串的数组吗？像这样吗？

const searchableFoods = {
  userX: [Apple, Pear],
  userY: [Carrot, Potato]
};

Answer 2

要求所有这些对象都放入单个对象中，而不要包含许多独立变量，然后可以使用简单的属性查找来获得适当的require ed值。另外，forEach可能会导致代码更具可读性，并且您可以单独传递函数名称（resolve），而不是为getWeight回调定义额外的匿名函数：

const foods = {
  Apple: require('../classses/Apple'),
  Pear: require('../classes/Pear),
  Carrot: require('../classes/Carrot),
  Potato: require('../classes/Potato)
};

// ...

searchableFoods[user].forEach((foodName) => {
  promises[foodName] = new Promise((resolve) => {
    foods[foodName].getWeight(arg1, resolve);
  });
});

Answer 3

您正在尝试访问getWeight作为字符串'Apple'的属性，而不是要导入的实际对象Apple的属性。

将子集数组更改为类似的内容

const searchableFoods = {
  userX: [Apple, Pear],
  userY: [Carrot, Potato]
};

将最终代码设为

const Apple = require('../classses/Apple');
const Pear = require('../classes/Pear);
const Carrot = require('../classes/Carrot);
const Potato = require('../classes/Potato);

const promises = {};
const user = 'userX'  // This is the inputted info, could also equal 'userY'.
const searchableFoods = {
  userX: [Apple, Pear],
  userY: [Carrot, Potato]
};

for (i = 0; i < searchableFoods[user].length; ++i) {
  promises[searchableFoods[user][i]] = new Promise(function(resolve, reject) {
    // Below line should behave like: Apple.getWeight(arg1, function....
    searchableFoods[user][i].getWeight(arg1, function(response) {
      resolve(response);
    })
  })
}

在动态命名的对象中调用方法

3 个答案: