September 2022
Intermediate to advanced
585 pages
8h 17m
Chinese
Content preview from JavaScript 经典实例：第三版
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第
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堆栈溢出）。如果一个对象引用的对象又引用原对象，这还算简单的，比这复杂的
情况处处可见。
还有一种情况是一个对象中有对同一个对象的两个引用。假如有一个
ProductCatalog
对象，它的某个属性保存着一个由
Product
对象构成的数组，其
中部分
Product
对象引用同一个
Supplier
对象。如果想得简单一些，就会创建多
个
Supplier
副本，对应每一个
Product
对象。而更完善的实现，例如
Lodash
库的
cloneDeep()
方法，在拷贝的过程中会记录引用，确保不多次创建同一个对象（如
果有人妄想自己重造轮子，可以看一下
Lodash
库对克隆的实现（
https://github.com/
lodash/lodash/blob/master/.internal/baseClone.js
），相信你肯定会知难而退）。
另一种经常被人推荐的克隆方法是通过
JSON
序列化把对象转换成字符串表示形
式，然后再转换回来。如果遇到
Date
对象（将变成字符串）、特殊的值（例如
Infinity
）和包含函数（将被丢弃）的自定义对象，这种方法也无能为力。最糟的是，
信息缺失，你却浑然不知。
测试两个对象是否相等时也要考虑这些事项。
===
运算符只判断两个变量是
否指向同一个对象。如果是两个具有相同数据的独立对象，
===
运算符返
回
false
。你可以实现一种通用的方式，找出两个对象的所有属性，然后
一一比较。然而，怎样才算相等要看比较的数据是什么类型，因此自己编写
isEqual()
函数始终是最安全的方法。 ...
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