ES6学习——集合（Collections）：WeakMap 应用示例

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这里看一下如何利用weakset实现class属性的私有化：

var Person = (function() {    var private = new WeakMap();    function Person(name) {        var privateProperties = {            name: name        };        private.set(this, privateProperties);    }    Person.prototype.getName = function() {        return private.get(this).name;    };    return Person;}());var p = new Person('John');print('Person 4 name: ' + p.getName());delete p.name;print('Person 4 name: ' + p.getName() + ' — stays private.');print('Person 4 properties: ' + Object.getOwnPropertyNames(p));

这样实现起来确实有点复杂，但看起来比较正规。而且这个场合正是weakset发挥作用的场景，因为weakset是弱引用，不会影响垃圾收集。

下面还有个例子是模拟java中compareTo的实现，在数组排序的时候可以使用：

var Person = (function() {    var private = new WeakMap();    function Person(name) {        var privateProperties = {            name: name        };        private.set(this, privateProperties);    }    Person.prototype.compareTo = function(other) {        var thisName = private.get(this).name;        var otherName = private.get(other).name;        return thisName.localeCompare(otherName);    };    Person.prototype.toString = function() {        return private.get(this).name;    };    return Person;}());var people = [    new Person('John'),    new Person('Jane'),    new Person('Jim')];people.sort(function(first, second) {    return first.compareTo(second);});print('Sorted people: ' + people.join(', '));

*以上代码引自：https://curiosity-driven.org/private-properties-in-javascript

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