Introduction to JSON

What is JSON?

1. JSON (JavaScript Object Notation) is a lightweight data-interchange format.
2. JSON is easy for humans to read and write.
3. JSON is easy for machines to parse and generate.
4. JSON is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition – December 1999.
5. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

JSON is built on two structures:

1. A collection of name/value pairs: In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.

2. An ordered list of values: In most languages, this is realized as an array, vector, list, or sequence.

These are universal data structures. Virtually all modern programming languages support them in one form or another. It makes sense that a data format that is interchangeable with programming languages also be based on these structures.

About format

You can freely insert formatting characters such as blanks, tabs, newlines

Representation of string

Strings are enclosed in double quotation marks (they can not be enclosed by single quotes)

Numeric expression

1. You can express integers, decimals, and exponents
2. You can not use hexadecimal or octal notation
3. NaN value and Infinity value can not be used

Representation of null value

1. Write as null
2. Undefined value can not be used