javascript - 什么是 JSON 安全对象？

Question

在凯尔辛普森的书中 You Don't Know JS: this & Object Prototypes , 他写了这篇关于如何复制对象的主题:

One subset solution is that objects which are JSON-safe (that is, can be serialized to a JSON string and then re-parsed to an object with the same structure and values) can easily be duplicated with:

var newObj = JSON.parse( JSON.stringify( someObj ) );

Of course, that requires you to ensure your object is JSON safe. For some situations, that's trivial. For others, it's insufficient.

什么是“JSON 安全”对象？我用 JavaScript 运行了一些测试，到目前为止，大多数东西(数组、数字、字符串、对象)都可以使用上面的行复制，除了方法(foo.bar)，当试图复制一个方法，undefined 被插入到复制对象中方法的位置。

Answer 1

要让 foo<=> JSON.parse(JSON.stringify(foo)) 为真，我们必须能够表示 foo 在 JSON format .

JSON 只支持:

Number: a signed decimal number that may contain a fractional part and may use exponential E notation, but cannot include non-numbers like NaN. The format makes no distinction between integer and floating-point. JavaScript uses a double-precision floating-point format for all its numeric values, but other languages implementing JSON may encode numbers differently.

String: a sequence of zero or more Unicodecharacters. Strings are delimited with double-quotation marks and support a backslash escaping syntax.

Boolean: either of the values true or false

Array: an ordered list of zero or more values, each of which may be of any type. Arrays use square bracket notation with elements being comma-separated.

Object: an unordered collection of name/value pairs where the names (also called keys) are strings. Since objects are intended to represent associative arrays,[12] it is recommended, though not required,[13] that each key is unique within an object. Objects are delimited with curly brackets and use commas to separate each pair, while within each pair the colon ':' character separates the key or name from its value.

null: An empty value, using the word null

在javascript中，JSON safe object的概念基本上是指可以无损地用JSON格式表示的javascript对象。