即时创建Javascript对象

Question

我相信我已经在jquery中看到了一些这样的例子.但对我来说,以下代码不起作用.firebug调试器告诉我:'位置未定义'.你能告诉我这是否可行？

function ResolveGeoCode() {
    var Location;
    Location.Ad1 = "Hello ";
    Location.Ad2 = "World";

    return Location;
}

var loc = ResolveGeoCode();
var String1 = loc.Ad1; //This contains "Hello "?
var String2 = loc.Ad2; //This contains "World"?

可以给我正在寻找的这类功能一个名字吗？

谢谢.

Answer 1

这就是发生的事情:

function ResolveGeoCode() {
    // Location is declared, but its value is `undefined`, not `object`
    var Location;
    alert(typeof Location); // <- proof pudding

    // Failing here because you're trying to add a 
    // property to an `undefined` value

    Location.Ad1 = "Hello "; 
    Location.Ad2 = "World";

    return Location;
}

Location在尝试向其添加属性之前,通过将其声明为空对象文字来修复它:

function ResolveGeoCode() {
    var Location = {};
    alert(typeof Location); // now it's an object

    // Programmatically add properties
    Location.Ad1 = "Hello "; 
    Location.Ad2 = "World";

    return Location;
}

如果您提前知道属性及其相应的值,则可以使用更内联的方法:

function ResolveGeoCode() {
    var Location = {
        Ad1: "Hello ",
        Ad2: "World"
    };

    // ...further manipulations of Location here... 

    return Location;
}

阅读此处了解有关对象文字的更多信息.

Answer 2

这是内联对象创建的语法（在本例中从函数返回。）。

function ResolveGeoCode() {
    return {
        Ad1: "Hello ",
        Ad2: "World"
    };
}