JavaScript - 原型(prototype)

Question

我正在努力获得更好的 JavaScript 实用知识。所以，我买了 Douglas Crockford 的书“JavaScript the good parts”。

我现在很难掌握原型(prototype)。在我点击//PROTOTYPE Example 之前，下面的所有内容似乎都可以在我的浏览器中使用。有人可以看看它，看看为什么我无法从中获得任何输出。 (除非我注释掉所有原型(prototype)代码，否则我的页面返回空白)

感谢您的帮助。

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

您在分配给 object.create 的函数表达式末尾缺少右大括号，而且您还没有在 object.create = function(o) { 中将 Object 大写。

//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