JavaScript代码复用模式实例分析

function inherit(C, P) { C.prototype = new P();}
// 父构造函数function Parent(name) { this.name = name || 'Adam';}
// 给原型添加say功能Parent.prototype.say = function () { return this.name;};
// Child构造函数为空function Child(name) {}
// 执行继承inherit(Child, Parent);var kid = new Child();console.log(kid.say());
// "Adam"var kiddo = new Child();kiddo.name = "Patrick";console.log(kiddo.say());
// "Patrick"// 缺点:不能让参数传进给Child构造函数var s = new Child('Seth');console.log(s.say());
// "Adam"这种模式的缺点是Child不能传进参数，基本上也就废了。

// 父构造函数function Parent(name) { this.name = name || 'Adam';}
// 给原型添加say功能Parent.prototype.say = function () { return this.name;};
// Child构造函数function Child(name) { Parent.apply(this, arguments);}var kid = new Child("Patrick");console.log(kid.name);
// "Patrick"// 缺点：没有从构造函数上继承say方法console.log(typeof kid.say);
// "undefined"缺点也很明显，say方法不可用，因为没有继承过来。

function inherit(C, P) { C.prototype = P.prototype;}
// 父构造函数function Parent(name) { this.name = name || 'Adam';}
// 给原型添加say功能Parent.prototype.say = function () { return this.name;};
// Child构造函数function Child(name) {}inherit(Child, Parent);var kid = new Child('Patrick');console.log(kid.name);
// undefinedconsole.log(typeof kid.say);
// functionkid.name = 'Patrick';console.log(kid.say());
// Patrickconsole.dir(kid);确定还是一样，Child的参数没有正确接收到。

/* 闭包 */var inherit = (function () { var F = function () { }; return function (C, P) { F.prototype = P.prototype; C.prototype = new F(); C.uber = P.prototype; CC.prototype.constructor = C; }} ());function Parent(name) { this.name = name || 'Adam';}// 给原型添加say功能Parent.prototype.say = function () { return this.name;};// Child构造函数function Child(name) {}inherit(Child, Parent);var kid = new Child();console.log(kid.name); // undefinedconsole.log(typeof kid.say); // functionkid.name = 'Patrick';console.log(kid.say()); // Patrickvar kid2 = new Child("Tom");console.log(kid.say()); console.log(kid.constructor.name); // Childconsole.log(kid.constructor === Parent); // false问题照旧，Child不能正常接收参数。

模式6：klass
这个模式，先上代码吧：
var klass = function (Parent, props) { var Child, F, i; //
1. // 新构造函数 Child = function () { if (Child.uber && Child.uber.hasOwnProperty("__construct")) { Child.uber.__construct.apply(this, arguments); } if (Child.prototype.hasOwnProperty("__construct")) { Child.prototype.__construct.apply(this, arguments); } }; //
2. // 继承 ParentParent = Parent || Object; F = function () { }; F.prototype = Parent.prototype; Child.prototype = new F(); Child.uber = Parent.prototype; ChildChild.prototype.constructor = Child; /
3. // 添加实现方法 for (i in props) { if (props.hasOwnProperty(i)) { Child.prototype[i] = props[i]; } }
// return the "class" return Child;};var Man = klass(null, { __construct: function (what) { console.log("Man's constructor"); this.name = what; }, getName: function () { return this.name; }});var first = new Man('Adam');
// logs "Man's constructor"first.getName();
// "Adam"var SuperMan = klass(Man, { __construct: function (what) { console.log("SuperMan's constructor"); }, getName: function () { var name = SuperMan.uber.getName.call(this); return "I am " + name; }});var clark = new SuperMan('Clark Kent');clark.getName();
// "I am Clark Kent"console.log(clark instanceof Man);
// trueconsole.log(clark instanceof SuperMan);