javascript - 复制带有 setter/getter 结果的对象

我有一个包含 setter/getter 的对象。

myObject {
    id: "MyId",
    get title () { return myRepository.title; }
}

myRepository.title = "MyTitle";

我想获得一个像这样的对象:

myResult = {
    id: "MyId",
    title: "MyTitle"
}

我不想复制 setter/getter ，所以:

myResult.title;                       // Returns "MyTitle"
myRepository.title = "Another title";
myResult.title;                       // Should still return "MyTitle"

我试过了:

$ .extend():但是它不会遍历getter。 http://bugs.jquery.com/ticket/6145

像建议的here一样迭代属性，但不会迭代getter。

当我使用angular时，使用Angular.forEach，如here所示。但是我只会得到属性，而不会得到 setter/getter 。

任何的想法？谢谢!

更新
我使用Object.defineProperty将 setter/getter 设置为:

 "title": { get: function () { return myRepository.title; }},

可以在文档中阅读:

设置可枚举:真正解决问题。

"title": { get: function () { return myRepository.title; }, enumerable: true },

最佳答案

$.extend正是您想要的。 (更新:从那以后，您就说过您还想要不可枚举的属性，因此它不能满足您的要求；请参阅下面的答案的第二部分，但我将第一部分留给其他人。)该错误并不是说生成的对象没有title属性，而是说生成的对象的title属性不会是 setter/getter ，这对于您想要的内容来说是完美的。

正确的getter语法示例:

// The myRepository object
var myRepository = { title: "MyTitle" };

// The object with a getter
var myObject = {
    id: "MyId",
    get title() { return myRepository.title; }
};

// The copy with a plain property
var copy = $.extend({}, myObject);

// View the copy (although actually, the result would look
// the same either way)
snippet.log(JSON.stringify(copy));

// Prove that the copy's `title` really is just a plain property:
snippet.log("Before: copy.title = " + copy.title);
copy.title = "foo";
snippet.log("After:  copy.title = " + copy.title);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

语法修复:

添加了缺少的var，=和;

删除重复属性title

更正了 setter/getter 声明语法

如果要包括不可枚举的属性，则需要使用Object.getOwnPropertyNames，因为它们不会出现在for-in循环，Object.keys或$.extend中(无论它们是“getter”还是常规属性):

// The myRepository object
var myRepository = { title: "MyTitle" };

// The object with a getter
var myObject = {
    id: "MyId"
};
Object.defineProperty(myObject, "title", {
  enumerable: false, // it's the default, this is just for emphasis,
  get: function() {
    return myRepository.title;
  }
});

snippet.log("$.extend won't visit non-enumerable properties, so we only get id here:");
snippet.log(JSON.stringify($.extend({}, myObject)));

// Copy it
var copy = Object.getOwnPropertyNames(myObject).reduce(function(result, name) {
  result[name] = myObject[name];
  return result;
}, {});

// View the copy (although actually, the result would look
// the same either way)
snippet.log("Our copy operation with Object.getOwnPropertyNames does, though:");
snippet.log(JSON.stringify(copy));

// Prove that the copy's `title` really is just a plain property:
snippet.log("Before: copy.title = " + copy.title);
copy.title = "foo";
snippet.log("After:  copy.title = " + copy.title);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

关于javascript - 复制带有 setter/getter 结果的对象，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/26863564/