JavaScript - 原型

Question

我正在努力获得更好的JavaScript工作知识.所以,我已经买了道格拉斯·克罗克福德的书"JavaScript的好部分".

我现在很难掌握Prototype.下面的所有内容似乎都在我的浏览器中工作,直到我点击// PROTOTYPE示例.有人可以看看它,看看为什么我不能从中得到任何输出.(除非我将所有原型代码注释掉,否则我的页面将返回空白)

谢谢你的帮助.

巴里

var stooge = { 
    "first-name": "Jerome",
    "last-name": "Howard",
    "nickname": "J", 
    "profession" : 'Actor' 
};

// below is augmenting
var st = stooge;
st.nickname = "curly";
// st.nickname and nick are the same because both are ref's to the same object 
var nick = st.nickname;


document.writeln(stooge['first-name']);  //expect Jerome -- this is "suffix" retrieval 
document.writeln(st.nickname); //expect "curly" -- this is "notation" retrieval
document.writeln(nick); //expect "curly"
document.writeln(stooge.profession); 


//PROTOTYPE EXAMPLE; 
if (typeof Object.create !== 'function')
{
    object.create = function(o) {
            var F = function () {}; 
            F.prototype = o; 
            return new F();
};
var another_stooge = Object.create(stooge);
another_stooge['first-name'] = 'Barry'; 
document.writeln(another_stooge['first-name']);
// the below should be inherited from the prototype therefore "Actor" 
document.writeln(another_stooge.profession);

Answer 1

你在分配给object.create的函数表达式的末尾缺少一个右括号,而且你还没有大写的Object object.create = function(o) {.

//PROTOTYPE EXAMPLE; 
if (typeof Object.create !== 'function')
{
    Object.create = function(o) {  // <--- "Object" instead of "object"
        var F = function () {}; 
        F.prototype = o; 
        return new F();
    };
}  // <--- Closing brace was missing