The JSON object contains methods for parsing JavaScript Object Notation (JSON) and converting values to JSON. It can't be called or constructed, and aside from its two method properties, it has no interesting functionality of its own.

Description

JavaScript and JSON differences

JSON is a syntax for serializing objects, arrays, numbers, strings, booleans, and null . It is based upon JavaScript syntax but is distinct from it: some JavaScript is not JSON.

Objects and Arrays Property names must be double-quoted strings; trailing commas are forbidden. Numbers Leading zeros are prohibited. A decimal point must be followed by at least one digit. NaN and Infinity are unsupported. Any JSON text is a valid JavaScript expression... ...But only in JavaScript engines that have implemented the proposal to make all JSON text valid ECMA-262. In engines that haven't implemented the proposal, U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR are allowed in string literals and property keys in JSON; but their use in these features in JavaScript string literals is a SyntaxError .

Consider this example where JSON.parse() parses the string as JSON and eval executes the string as JavaScript:

let code = '"\u2028\u2029"' JSON.parse(code) // evaluates to "\u2028\u2029" in all engines eval(code) // throws a SyntaxError in old engines

Other differences include allowing only double-quoted strings and having no provisions for undefined or comments. For those who wish to use a more human-friendly configuration format based on JSON, there is JSON5, used by the Babel compiler, and the more commonly used YAML.

Full JSON syntax

The full JSON syntax is as follows:

JSON = null or true or false or JSONNumber or JSONString or JSONObject or JSONArray JSONNumber = - PositiveNumber or PositiveNumber PositiveNumber = DecimalNumber or DecimalNumber . Digits or DecimalNumber . Digits ExponentPart or DecimalNumber ExponentPart DecimalNumber = 0 or OneToNine Digits ExponentPart = e Exponent or E Exponent Exponent = Digits or + Digits or - Digits Digits = Digit or Digits Digit Digit = 0 through 9 OneToNine = 1 through 9 JSONString = "" or " StringCharacters " StringCharacters = StringCharacter or StringCharacters StringCharacter StringCharacter = any character except " or \ or U+0000 through U+001F or EscapeSequence EscapeSequence = \" or \/ or \\ or \b or \f or

or \r or \t or \u HexDigit HexDigit HexDigit HexDigit HexDigit = 0 through 9 or A through F or a through f JSONObject = { } or { Members } Members = JSONString : JSON or Members , JSONString : JSON JSONArray = [ ] or [ ArrayElements ] ArrayElements = JSON or ArrayElements , JSON

Insignificant whitespace may be present anywhere except within a JSONNumber (numbers must contain no whitespace) or JSONString (where it is interpreted as the corresponding character in the string, or would cause an error). The tab character (U+0009), carriage return (U+000D), line feed (U+000A), and space (U+0020) characters are the only valid whitespace characters.

Static methods

JSON.parse( text [, reviver ]) Parse the string text as JSON, optionally transform the produced value and its properties, and return the value. Any violations of the JSON syntax, including those pertaining to the differences between JavaScript and JSON, cause a SyntaxError to be thrown. The reviver option allows for interpreting what the replacer has used to stand in for other datatypes. JSON.stringify( value [, replacer [, space ]]) Return a JSON string corresponding to the specified value, optionally including only certain properties or replacing property values in a user-defined manner. By default, all instances of undefined are replaced with null , and other unsupported native data types are censored. The replacer option allows for specifying other behavior.

Examples

Example JSON

{ "browsers": { "firefox": { "name": "Firefox", "pref_url": "about:config", "releases": { "1": { "release_date": "2004-11-09", "status": "retired", "engine": "Gecko", "engine_version": "1.7" } } } } }

Specifications

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. Update compatibility data on GitHub Desktop Mobile Server Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet Node.js JSON Chrome Full support 3 Edge Full support 12 Firefox Full support 3.5 IE Full support 8 Opera Full support 10.5 Safari Full support 4 WebView Android Full support ≤37 Chrome Android Full support 18 Firefox Android Full support 4 Opera Android Full support 11 Safari iOS Full support 4 Samsung Internet Android Full support 1.0 nodejs Full support 0.1.100 JavaScript is a superset of JSON Chrome Full support 66 Edge Full support 79 Firefox Full support 62 IE No support No Opera Full support 53 Safari Full support 12 WebView Android Full support 66 Chrome Android Full support 66 Firefox Android Full support 62 Opera Android Full support 47 Safari iOS Full support 12 Samsung Internet Android Full support 9.0 nodejs Full support 10.0.0 parse Chrome Full support 3 Edge Full support 12 Firefox Full support 3.5 IE Full support 8 Opera Full support 10.5 Safari Full support 4 WebView Android Full support ≤37 Chrome Android Full support 18 Firefox Android Full support 4 Opera Android Full support 11 Safari iOS Full support 4 Samsung Internet Android Full support 1.0 nodejs Full support 0.1.100 stringify Chrome Full support 3 Edge Full support 12 Firefox Full support 3.5 IE Full support 8 Opera Full support 10.5 Safari Full support 4 WebView Android Full support ≤37 Chrome Android Full support 18 Firefox Android Full support 4 Opera Android Full support 11 Safari iOS Full support 4 Samsung Internet Android Full support 1.0 nodejs Full support 0.1.100 Legend Full support Full support No support No support

See also