javascript - 为什么这些 JavaScript 函数不添加到该对象中？

Question

我想为基于 Json 文件的对象编写 getter 和 setter 函数。我复制了 John Resig 的书(Appress Pro JavaScript Techniques)中的以下代码，但它不起作用，并且这些函数没有添加到对象中。你能告诉我为什么以及正确的代码是什么吗？

// Create a new user object that accepts an object of properties
function User(properties) {
// Iterate through the properties of the object, and make sure
// that it's properly scoped (as discussed previously)
  for (var i in properties) {
    (function () {
        // Create a new getter for the property
        this["get" + i] = function () {
            return properties[i];
        };

        // Create a new setter for the property
        this["set" + i] = function (val) {
            properties[i] = val;
        };
    })();
  }
}

// Create a new user object instance and pass in an object of
// properties to seed it with
var user = new User({
name: "Bob",
age: 44
});

// Just note that the name property does not exist, as it's private
// within the properties object
//alert( user.name == null );

// However, we're able to access its value using the new getname()
// method, that was dynamically generated
alert(user.getname());

Answer 1

您使用了一个函数来创建一个闭包，但您忘记将 i 传递给它。您还需要在函数内对 this 进行不同的引用，因为其中的上下文会更改为 window。

function User(properties) {
    var i, me = this;
    for (i in properties) (function (i) {
        // Create a new getter for the property
        me["get" + i] = function () { // using `me` because `this !== me`
            return properties[i];
        };

        // Create a new setter for the property
        me["set" + i] = function (val) {
            properties[i] = val;
        };
    }(i)); // i passed into function closure
}