Question

我能够得到第一个参数iAmDog，this也可以访问第一个参数，如何传递第二个参数iAmCat并打印出来？

var speak = function(iAmDog, iAmCat) {
  console.log(this);

  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = {
  normal: "moof",
  love: 'woow'
};
var speakAsCat = {
  normal: "meow",
  love: 'purr'
};

speak.call(speakAsDog, speakAsCat);

Answer 1

你的代码只是错综复杂的错别字。此外，您不必显式调用.call()函数。

var speak = function (iAmDog, iAmCat) {
  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = { normal: "moof", love: 'woow' };
var speakAsCat = { normal: "meow", love: 'purr' };

speak(speakAsDog, speakAsCat);

Answer 2

function.call和function.apply中的第一个参数是thisArg，它在函数内可用作this值。因此，如果你想传递任何参数，你应该从第二个开始。在你的情况下，你可以发送null作为thisArg，因为这不会在函数内部引用。

var speak = function(iAmDog, iAmCat) {
  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = { normal: "moof", love: 'woow' };
var speakAsCat = { normal: "meow", love: 'purr' };

speak.call(null, speakAsDog, speakAsCat);
speak.apply(null, [speakAsDog, speakAsCat]);

Answer 3

根据FrankerZ的建议，您可能不需要call或apply但是如果您需要更改上下文变量，您可以使用call或

var speak = function(iAmCat) {
  var iAmDog = this;
  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = {
  normal: "moof",
  love: 'woow'
};
var speakAsCat = {
  normal: "meow",
  love: 'purr'
};

speak.call(speakAsDog, speakAsCat);

使用apply或

var speak = function() {
  var iAmDog = this,
    iAmCat = arguments[0];
  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = {
  normal: "moof",
  love: 'woow'
};
var speakAsCat = {
  normal: "meow",
  love: 'purr'
};

speak.apply(speakAsDog, [speakAsCat]);

使用bind。

var speak = function(iAmCat) {
  var iAmDog = this;
  console.log(iAmDog.love);
  console.log(iAmDog.normal);

  console.log(iAmCat.love);
  console.log(iAmCat.normal);
};

var speakAsDog = {
  normal: "moof",
  love: 'woow'
};
var speakAsCat = {
  normal: "meow",
  love: 'purr'
};
var newFN = speak.bind(speakAsDog);
newFN(speakAsCat);

如何将两个/多个对象作为参数传递给函数

3 个答案: