Question

在阅读一本书（JavaScript：权威指南）时，我发现了一段在ES3中实现 Object.create 的代码：

// inherit() returns a newly created object that inherits properties from the
// prototype object p. It uses the ECMAScript 5 function Object.create() if
// it is defined, and otherwise falls back to an older technique.
function inherit(p) {
if (p == null) throw TypeError(); // p must be a non-null object
if (Object.create)
// If Object.create() is defined...
return Object.create(p);
//
then just use it.
var t = typeof p;
// Otherwise do some more type checking
if (t !== "object" && t !== "function") throw TypeError();
function f() {};
// Define a dummy constructor function.
f.prototype = p;
// Set its prototype property to p.
return new f();
// Use f() to create an "heir" of p.
}

并且有我的实施：

function inherit(proto) {
        var o = {};

        if(typeof proto != "function" && typeof proto != "object")
                throw TypeError();

        o.prototype = proto;
        return o;
}

我不明白为什么书籍作者创建了一个函数并将其用作构造函数来返回具有原型 p 的新对象，而它可能只是 o.prototype = proto

Object.create实现ES3

0 个答案: