From da78a9e329e272dedb2400b79a3bdeebff387d47 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:42:17 -0500 Subject: initial commit --- .../reference/global_objects/json/index.html | 244 +++++++++++++++++++++ 1 file changed, 244 insertions(+) create mode 100644 files/it/web/javascript/reference/global_objects/json/index.html (limited to 'files/it/web/javascript/reference/global_objects/json/index.html') diff --git a/files/it/web/javascript/reference/global_objects/json/index.html b/files/it/web/javascript/reference/global_objects/json/index.html new file mode 100644 index 0000000000..caa08b766f --- /dev/null +++ b/files/it/web/javascript/reference/global_objects/json/index.html @@ -0,0 +1,244 @@ +--- +title: JSON +slug: Web/JavaScript/Reference/Global_Objects/JSON +tags: + - JSON + - JavaScript + - NeedsTranslation + - Object + - Reference + - TopicStub + - polyfill +translation_of: Web/JavaScript/Reference/Global_Objects/JSON +--- +
{{JSRef}}
+ +

The JSON object contains methods for parsing JavaScript Object Notation ({{glossary("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 Object Notation

+ +

JSON is a syntax for serializing objects, arrays, numbers, strings, booleans, and {{jsxref("null")}}. It is based upon JavaScript syntax but is distinct from it: some JavaScript is not JSON, and some JSON is not JavaScript. See also JSON: The JavaScript subset that isn't.

+ + + + + + + + + + + + + + + + + + + + + + + +
JavaScript and JSON differences
JavaScript typeJSON differences
Objects and ArraysProperty names must be double-quoted strings; trailing commas are forbidden.
NumbersLeading zeros are prohibited; a decimal point must be followed by at least one digit.
Strings +

Only a limited sets of characters may be escaped; certain control characters are prohibited; the Unicode line separator (U+2028) and paragraph separator (U+2029) characters are permitted; strings must be double-quoted. See the following example where {{jsxref("JSON.parse()")}} works fine and a {{jsxref("SyntaxError")}} is thrown when evaluating the code as JavaScript:

+ + 
+var code = '"\u2028\u2029"';
+JSON.parse(code); // works fine
+eval(code); // fails
+
+
+ +

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 \n 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.

+ +

Methods

+ +
+
{{jsxref("JSON.parse()")}}
+
Parse a string as JSON, optionally transform the produced value and its properties, and return the value.
+
{{jsxref("JSON.stringify()")}}
+
Return a JSON string corresponding to the specified value, optionally including only certain properties or replacing property values in a user-defined manner.
+
+ +

Polyfill

+ +

The JSON object is not supported in older browsers. You can work around this by inserting the following code at the beginning of your scripts, allowing use of JSON object in implementations which do not natively support it (like Internet Explorer 6).

+ +

The following algorithm is an imitation of the native JSON object:

+ +
if (!window.JSON) {
+  window.JSON = {
+    parse: function(sJSON) { return eval('(' + sJSON + ')'); },
+    stringify: (function () {
+      var toString = Object.prototype.toString;
+      var isArray = Array.isArray || function (a) { return toString.call(a) === '[object Array]'; };
+      var escMap = {'"': '\\"', '\\': '\\\\', '\b': '\\b', '\f': '\\f', '\n': '\\n', '\r': '\\r', '\t': '\\t'};
+      var escFunc = function (m) { return escMap[m] || '\\u' + (m.charCodeAt(0) + 0x10000).toString(16).substr(1); };
+      var escRE = /[\\"\u0000-\u001F\u2028\u2029]/g;
+      return function stringify(value) {
+        if (value == null) {
+          return 'null';
+        } else if (typeof value === 'number') {
+          return isFinite(value) ? value.toString() : 'null';
+        } else if (typeof value === 'boolean') {
+          return value.toString();
+        } else if (typeof value === 'object') {
+          if (typeof value.toJSON === 'function') {
+            return stringify(value.toJSON());
+          } else if (isArray(value)) {
+            var res = '[';
+            for (var i = 0; i < value.length; i++)
+              res += (i ? ', ' : '') + stringify(value[i]);
+            return res + ']';
+          } else if (toString.call(value) === '[object Object]') {
+            var tmp = [];
+            for (var k in value) {
+              if (value.hasOwnProperty(k))
+                tmp.push(stringify(k) + ': ' + stringify(value[k]));
+            }
+            return '{' + tmp.join(', ') + '}';
+          }
+        }
+        return '"' + value.toString().replace(escRE, escFunc) + '"';
+      };
+    })()
+  };
+}
+
+ +

More complex well-known polyfills for the JSON object are JSON2 and JSON3.

+ +

Specifications

+ + + + + + + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('ES5.1', '#sec-15.12', 'JSON')}}{{Spec2('ES5.1')}} 
{{SpecName('ES6', '#sec-json-object', 'JSON')}}{{Spec2('ES6')}} 
+ +

Browser compatibility

+ +
{{CompatibilityTable}}
+ +
+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatVersionUnknown}}{{CompatGeckoDesktop("1.9.1")}}{{CompatIE("8.0")}}{{CompatOpera("10.5")}}{{CompatSafari("4.0")}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatGeckoMobile("1.0")}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +

See also

+ + -- cgit v1.2.3-54-g00ecf