Javascript Object Literal Parser

Splits an object literal string into a set of top-level key-value pairs.

By Michael Best

License: MIT (http://www.opensource.org/licenses/mit-license.php)

Exports a single function, parseObjectLiteral(str) that accepts an object literal string (with or without enclosing braces) and returns an array of key-value string pairs. The key are strings, but unquoted keys are accepted as long as they don't contain these special characters: ,:()[]{}'"/. The value is any valid Javascript expression; the parser will return it as a string (without evaluating it).

Notes: This parser is more lenient than a standard JavaScript parser, accepting unquoted keys with special characters and accepting keys without a value. It also silently ignores errors such as a missing key (the value will be skipped). If a value expression contains unquoted spaces, they may be stripped in the result.

Acknowledgments: This parser's functionality is based on the parser included in Knockout 2.x by Steven Sanderson. The examples below are also based on the specs in Knockout. This parser's implementation is inspired by json-sans-eval by Mike Samuel. Compared to the Knockout 2.x parser, this one is smaller and about three times as fast. A version of this parser is now included in Knockout as of version 3.0.

Examples

• Simple object literals

  parseObjectLiteral("a: 1, b: 2, \"quotedKey\": 3, 'aposQuotedKey': 4");

  [ ["a","1"], ["b","2"], ["quotedKey","3"], ["aposQuotedKey","4"] ]

• With enclosing braces

  parseObjectLiteral("{a: 1}");

  [ ["a","1"] ]

• String values

  parseObjectLiteral(
        "a: \"comma, colon: brace{ bracket[ apos' escapedQuot\\\" end\","
      + "b: 'escapedApos\\' brace} bracket] quot\"'");

  [
      ["a","\"comma, colon: brace{ bracket[ apos' escapedQuot\\\" end\""],
      ["b","'escapedApos\\' brace} bracket] quot\"'"]
  ]

• Values with objects, arrays, function literals, and regular expressions

  parseObjectLiteral(
        "myObject:{someChild:{}, someChildArray:[1,2,3], \"quotedChildProp\":'string value'},\n"
      + "someFn:function(a,b,c){var regex=/}/g;var str='/})({';return{};},"
      + "myArray:[{}, function(){}, \"my'Str\", 'my\"Str']"
      );

  [
      ["myObject","{someChild:{},someChildArray:[1,2,3],\"quotedChildProp\":'string value'}"],
      ["someFn","function(a,b,c){var regex=/}/g;var str='/})({';return{};}"],
      ["myArray","[{},function(){},\"my'Str\",'my\"Str']"]
  ]

• Keys with special characters

  parseObjectLiteral("a.b: 1, b+c: 2, c=d: 3, d_e: 4");

  [ ["a.b","1"], ["b+c","2"], ["c=d","3"], ["d_e","4"] ]

• Keys without values, values without keys, etc.

  parseObjectLiteral("keyonly, 'key:quoted', key:, {nokey: 4}");

  [ ["keyonly",undefined], ["key:quoted",undefined], ["key",undefined], [undefined,"{nokey:4}"] ]