example.js

var json;

json = [
  {
    foo: {
      bar: ['ka', 'boom']
    }
  }, {
    foo: {
      bar: ['sna', 'fu']
    }
  }, {
    foo: {
      bar: {
        rab: 'oof'
      }
    }
  }
];

console.log(JSON.lookup('foo.bar[1]=/(boom|fu)/', json, true));

/// OUTPUTS

[ {
    foo: {
      bar: ['ka', 'boom']
    }
  }, {
    foo: {
      bar: ['sna', 'fu']
    }
  } ]

json-lookup.js

/*
	json-lookup v1.0
*/

!function(){
 "use strict"
 
var getvalcheck, json, lookup, parseQuery;

getvalcheck = function(expected) {
  var is_regex_match, tester;
  is_regex_match = /^\/.+\/$/;
  if (is_regex_match.test(expected)) {
    tester = new RegExp(expected.replace(/^\/|\/$/g, ''));
    return function(v) {
      return tester.test(v);
    };
  } else {
    return function(v) {
      return v === expected;
    };
  }
};

parseQuery = function(query) {
  var checkval, expected, has_value_check, paths;
  has_value_check = /\=.+$/;
  paths = query.replace(has_value_check, '');
  paths = paths.replace(/\.(\d+)\./, "[$1]");
  if (has_value_check.test(query)) {
    expected = query.substring(query.indexOf('=') + 1);
    checkval = getvalcheck(expected);
  } else {
    checkval = function() {
      return true;
    };
  }
  return {
    paths: paths,
    checkval: checkval
  };
};

lookup = function(query, json, multiple) {
  var collected, index, item, o, _len;
  if (query == null) query = '';
  if (json == null) json = [];
  if (multiple == null) multiple = false;
  if (query === '') return json;
  if (!(json instanceof Array)) json = [json];
  if (typeof query === 'number') return json[query];
  if (typeof query === 'string') query = parseQuery(query);
  collected = [];
  for (index = 0, _len = json.length; index < _len; index++) {
    item = json[index];
    o = (new Function("try{return this." + query.paths + "}catch(E){return null}")).call(item);
    if (query.checkval(o)) {
      if (multiple) {
        collected.push(item);
      } else {
        return item;
      }
    }
  }
  if (multiple) {
    return collected;
  } else {
    return null;
  }
};

if (typeof JSON.lookup !== "function") JSON.lookup = lookup;

}()