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    JSON Redirect 1

    Summary

    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 Object Notation

    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, and some JSON is not JavaScript. See also JSON: The JavaScript subset that isn't.

    JavaScript and JSON differences
    JavaScript type JSON differences
    Objects and Arrays Property names must be double-quoted strings; trailing commas are forbidden.
    Numbers Leading zeroes 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 JSON.parse works fine and a 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

    JSON.parse()
    Parse a string as JSON, optionally transform the produced value and its properties, and return the value.
    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 (vContent) {
          if (vContent instanceof Object) {
            var sOutput = "";
            if (vContent.constructor === Array) {
              for (var nId = 0; nId < vContent.length; sOutput += this.stringify(vContent[nId]) + ",", nId++);
                return "[" + sOutput.substr(0, sOutput.length - 1) + "]";
            }
            if (vContent.toString !== Object.prototype.toString) { 
              return "\"" + vContent.toString().replace(/"/g, "\\$&") + "\"";
            }
            for (var sProp in vContent) { 
              sOutput += "\"" + sProp.replace(/"/g, "\\$&") + "\":" + this.stringify(vContent[sProp]) + ",";
            }
            return "{" + sOutput.substr(0, sOutput.length - 1) + "}";
         }
         return typeof vContent === "string" ? "\"" + vContent.replace(/"/g, "\\$&") + "\"" : String(vContent);
        }
      };
    }
    

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

    Specifications

    Specification Status Comment
    ECMAScript Language Specification 5.1th Edition (ECMA-262) Standard  
    ECMAScript Language Specification 6th Edition (ECMA-262) Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) 3.5 (1.9.1) 8.0 10.5 4.0
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) 1.0 (1.0) (Yes) (Yes) (Yes)

    Based on Kangax's compat table.

    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy
    Last updated by: Sheppy,