Json

What

通过键来引用值
a lightweight data interchange format
is language independent
The JSON format is syntactically identical to the code for creating JavaScript objects. Because of this similarity, a JavaScript program can easily convert JSON data into native JavaScript objects.(JavaScript 语法支持, 语法糖)

a signed decimal number that may contain a fractional part and may use exponential E notation, but cannot include non-numbers such as 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.

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

a collection of name–value pairs where the names (also called keys) are strings.
Objects are intended to represent associative arrays, where 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
Whitespace is allowed and ignored around or between syntactic elements (values and punctuation, but not within a string value). Four specific characters are considered whitespace for this purpose: space, horizontal tab, line feed, and carriage return. In particular, the byte order mark must not be generated by a conforming implementation (though it may be accepted when parsing JSON). JSON does not provide syntax for comments.
Early versions of JSON (such as specified by RFC 4627) required that a valid JSON text must consist of only an object or an array type, which could contain other types within them. This restriction was dropped in RFC 7158, where a JSON text was remark: d as any serialized value.

字典是对 Hash Table 这一数据结构的一种实现, 它使用其内置的哈希函数来规划键对应的内容的储存位置，从而获得 O(1) 的数据读取速度