Appendix E. JSON

Farewell: the leisure and the fearful time Cuts off the ceremonious vows of love And ample interchange of sweet discourse, Which so long sunder'd friends should dwell upon: God give us leisure for these rites of love! Once more, adieu: be valiant, and speed well!

—William Shakespeare, The Tragedy of Richard the Third

JavaScript Object Notation (JSON) is a lightweight data interchange format. It is based on JavaScript's object literal notation, one of JavaScript's best parts. Even though it is a subset of JavaScript, it is language independent. It can be used to exchange data between programs written in all modern programming languages. It is a text format, so it is readable by humans and machines. It is easy to implement and easy to use. There is a lot of material about JSON at http://www.JSON.org/.

JSON Syntax

JSON has six kinds of values: objects, arrays, strings, numbers, booleans (true and false), and the special value null. Whitespace (spaces, tabs, carriage returns, and newline characters) may be inserted before or after any value. This can make JSON texts easier for humans to read. Whitespace may be omitted to reduce transmission or storage costs.

A JSON object is an unordered container of name/value pairs. A name can be any string. A value can be any JSON value, including arrays and objects. JSON objects can be nested to any depth, but generally it is most effective to keep them relatively flat. Most languages have a feature that maps easily to JSON objects, such as an object, struct, record, dictionary, hash table, property list, or associative array.

The JSON array is an ordered sequence of values. A value can be any JSON value, including arrays and objects. Most languages have a feature that maps easily onto JSON arrays, such as an array, vector, list, or sequence.

A JSON string is wrapped in double quotes. The \ character is used for escapement. JSON allows the / character to be escaped so that JSON can be embedded in HTML <script> tags. HTML does not allow the sequence </ except to start the </script> tag. JSON allows <\/, which produces the same result but does not confuse HTML.

JSON numbers are like JavaScript numbers. A leading zero is not allowed on integers because some languages use that to indicate the octal. That kind of radix confusion is not desirable in a data interchange format. A number can be an integer, real, or scientific.

That's it. That is all of JSON. JSON's design goals were to be minimal, portable, textual, and a subset of JavaScript. The less we need to agree on in order to interoperate, the more easily we can interoperate.

[
    {
        "first": "Jerome",
        "middle": "Lester",
        "last": "Howard",
        "nick-name": "Curly",
        "born": 1903,
        "died": 1952,
        "quote": "nyuk-nyuk-nyuk!"
    },
    {
        "first": "Harry",
        "middle": "Moses",
        "last": "Howard",
        "nick-name": "Moe",
        "born": 1897,
        "died": 1975,
        "quote": "Why, you!"
    },
    {
        "first": "Louis",
        "last": "Feinberg",
        "nick-name": "Larry",
        "born": 1902,
        "died": 1975,
        "quote": "I'm sorry. Moe, it was an accident!"
    }
]

Table of Contents for JavaScript: The Good Parts

Appendix E. JSON

JSON Syntax

Table of Contents for
JavaScript: The Good Parts