querystring.js

// Query String Utilities
// Taken from Jack

var DEFAULT_SEP = "&";
var DEFAULT_EQ = "=";

exports.unescape = function (str, decodeSpaces) {
    return decodeURIComponent(decodeSpaces ? str.replace(/\+/g, " ") : str);
};

exports.escape = function (str) {
    return encodeURIComponent(str);
};

exports.toQueryString = function (obj, sep, eq, name) {
    sep = sep || DEFAULT_SEP;
    eq = eq || DEFAULT_EQ;
	if (isA(obj, null) || isA(obj, undefined)) {
		return name ? encodeURIComponent(name) + eq : '';
	}
	if (isNumber(obj) || isString(obj)) {
		return encodeURIComponent(name) + eq + encodeURIComponent(obj);
	}
	if (isA(obj, [])) {
		var s = [];
		name = name+'[]';
		for (var i = 0, l = obj.length; i < l; i ++) {
			s.push( exports.toQueryString(obj[i], sep, eq, name) );
		}
		return s.join(sep);
	}
	// now we know it's an object.
	var s = [];
	var begin = name ? name + '[' : '';
	var end = name ? ']' : '';
	for (var i in obj) if (obj.hasOwnProperty(i)) {
		var n = begin + i + end;
		s.push(exports.toQueryString(obj[i], sep, eq, n));
	}
	return s.join(sep);
};

exports.parseQuery = function(qs, sep, eq) {
	return qs
		.split(sep||DEFAULT_SEP)
		.map(pieceParser(eq||DEFAULT_EQ))
		.reduce(mergeParams);
};

// Parse a key=val string.
// These can get pretty hairy
// example flow:
// parse(foo[bar][][bla]=baz)
// return parse(foo[bar][][bla],"baz")
// return parse(foo[bar][], {bla : "baz"})
// return parse(foo[bar], [{bla:"baz"}])
// return parse(foo, {bar:[{bla:"baz"}]})
// return {foo:{bar:[{bla:"baz"}]}}
var pieceParser = function (eq) {
    return function parsePiece (key, val) {
		if (arguments.length !== 2) {
			// key=val, called from the map/reduce
		 	key = key.split(eq);
			return parsePiece(
			    exports.unescape(key.shift(), true), exports.unescape(key.join(eq), true)
			);
		}
		key = key.replace(/^\s+|\s+$/g, '');
	    if (isString(val)) val = val.replace(/^\s+|\s+$/g, '');
		var sliced = /(.*)\[([^\]]*)\]$/.exec(key);
		if (!sliced) {
			var ret = {};
			if (key) ret[key] = val;
			return ret;
		}
		// ["foo[][bar][][baz]", "foo[][bar][]", "baz"]
		var tail = sliced[2], head = sliced[1];

		// array: key[]=val
		if (!tail) return parsePiece(head, [val]);

		// obj: key[subkey]=val
		var ret = {};
		ret[tail] = val;
		return parsePiece(head, ret);
	};
};

// the reducer function that merges each query piece together into one set of params
function mergeParams (params, addition) {
	return (
		// if it's uncontested, then just return the addition.
		(!params) ? addition
		// if the existing value is an array, then concat it.
		: (isA(params, [])) ? params.concat(addition)
		// if the existing value is not an array, arrayify it.
		: (!isA(params, {}) || !isA(addition, {})) ? [params].concat(addition)
		// else merge them as objects, which is a little more complex
		: mergeObjects(params, addition)
	)
};

// Merge two *objects* together. If this is called, we've already ruled
// out the simple cases, and need to do the for-in business.
function mergeObjects (params, addition) {
	for (var i in addition) if (i && addition.hasOwnProperty(i)) {
		params[i] = mergeParams(params[i], addition[i]);
	}
	return params;
};

// duck typing
function isA (thing, canon) {
	return (
		// truthiness. you can feel it in your gut.
		(!thing === !canon)
		// typeof is usually "object"
		&& typeof(thing) === typeof(canon)
		// check the constructor
		&& Object.prototype.toString.call(thing) === Object.prototype.toString.call(canon)
	);
};
function isNumber (thing) {
	return typeof(thing) === "number" && isFinite(thing);
};
function isString (thing) {
	return typeof(thing) === "string";
};