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如何在Javascript中正确创建新的Person对象?

closures javascript

TimDog · 技术社区 · 14 年前

;Person1 = (function() {
    function P (fname, lname) {
        P.FirstName = fname;
        P.LastName = lname;
        return P;
    }
    P.FirstName = '';
    P.LastName = '';
    var prName = 'private';
    P.showPrivate = function() { alert(prName); };
    return P;
})();

;Person2 = (function() {
    var prName = 'private';
    this.FirstName = '';
    this.LastName = ''; 
    this.showPrivate = function() { alert(prName); };
    return function(fname, lname) {
        this.FirstName = fname;
        this.LastName = lname;
    }   
})();

假设我这样调用它们:

var s = new Array();

//Person1
s.push(new Person1("sal", "smith"));
s.push(new Person1("bill", "wonk"));
alert(s[0].FirstName);
alert(s[1].FirstName);
s[1].showPrivate();

//Person2
s.push(new Person2("sal", "smith"));
s.push(new Person2("bill", "wonk"));
alert(s[2].FirstName);
alert(s[3].FirstName);
s[3].showPrivate();

Person1 showPrivate 功能,但本地 FirstName 变量被覆盖。

第二个 Person2 设置警报“sal”,然后设置“bill”,但是当函数被调用。这个 new 显示私人

如何确保闭包是具有公开方法的可重用对象?我正在使用(function(){//object code})();语法,以确保变量的作用域仅限于正在创建的对象。谢谢!

4 回复 | 直到 14 年前

house9 14 年前

这是使用douglascrockford的“JavaScript:thegoodparts”中的技术 http://oreilly.com/catalog/9780596517748

第5章:继承-功能部分

var personConstructor = function (spec) {
    var that = {};

    that.fullName = function () {
            return spec.first_name + " " + spec.last_name;
    };

    that.setFirstName = function (firstName) {
            spec.first_name = firstName;
    };

    return that;
};

var john = personConstructor({first_name: "John", last_name: "Doe"});
var jane = personConstructor({first_name: "Jane", last_name: "Doe"}); 

alert(john.fullName()); // John Doe
alert(jane.fullName()); // Jane Doe

john.first_name = "OVERWRITE";
alert(john.fullName()); // John Doe

john.setFirstName("OVERWRITE-VIA-SETTER");
alert(john.fullName()); // OVERWRITE-VIA-SETTER Doe

把这些放在jsfiddle上,如果你想试驾的话,可以链接到下面, 当页面加载时,请注意4个警报

http://jsfiddle.net/SecKg/

TimDog 14 年前

showPrivate 构造函数中的函数--确保函数是公共的:

;Person2 = (function() {
    var prName = 'private';
    return function(fname, lname) {
        this.FirstName = fname;
        this.LastName = lname;
        this.showPrivate = function() { alert(prName); };
    }
})();

steve_c 14 年前

您希望使用prototype方法来创建Person对象。

;(function(){
    function Person(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;

        function showPrivate() {
            alert(this.firstName);
        }
    }

    Person.prototype.getName = function() {
        return this.firstName + ' ' + this.lastName;
    }

})();

我不太清楚你想在这里完成什么。你的问题有点让人困惑。也许你想改写一下?

PDA 11 年前

//this would allow for instance:
//  john.setName('first', 'Johnny');
//  jane.setName('last', 'Smith');
var personConstructor = function (spec) {
    return {
        fullName: function () {
            return spec.first_name + " " + spec.last_name;
        },
        setName: function (nameType, name) {
            spec[nameType+'_name'] = name;
        }
    };
};