list.js

function deParam (params, coerce) {
	var obj = {};
	var coerce_types = { 'true': !0, 'false': !1, 'null': null };
	var decode = decodeURIComponent;

	// Iterate over all name=value pairs.
	$.each(params.replace(/\+/g, ' ').split('&'), function(j, v){
			var param = v.split( '=' ),
			key = decode(param[0]),
			val,
			cur = obj,
			i = 0,

			// If key is more complex than 'foo', like 'a[]' or 'a[b][c]', split it
			// into its component parts.
			keys = key.split(']['),
			keys_last = keys.length - 1;

			// If the first keys part contains [ and the last ends with ], then []
			// are correctly balanced.
			if (/\[/.test(keys[0]) && /\]$/.test(keys[keys_last])) {
			// Remove the trailing ] from the last keys part.
			keys[keys_last] = keys[keys_last].replace(/\]$/, '');

			// Split first keys part into two parts on the [ and add them back onto
			// the beginning of the keys array.
			keys = keys.shift().split('[').concat(keys);

			keys_last = keys.length - 1;
			} else {
				// Basic 'foo' style key.
				keys_last = 0;
			}

			// Are we dealing with a name=value pair, or just a name?
			if (param.length === 2) {
				val = decode(param[1]);

				// Coerce values.
				if (coerce) {
					val = val && !isNaN(val)            ? +val              // number
						: val === 'undefined'             ? undefined         // undefined
						: coerce_types[val] !== undefined ? coerce_types[val] // true, false, null
						: val;                                                // string
				}

				if (keys_last) {
					// Complex key, build deep object structure based on a few rules:
					// * The 'cur' pointer starts at the object top-level.
					// * [] = array push (n is set to array length), [n] = array if n is 
					//   numeric, otherwise object.
					// * If at the last keys part, set the value.
					// * For each keys part, if the current level is undefined create an
					//   object or array based on the type of the next keys part.
					// * Move the 'cur' pointer to the next level.
					// * Rinse & repeat.
					for ( ; i <= keys_last; i++) {
						key = keys[i] === '' ? cur.length : keys[i];
						cur = cur[key] = i < keys_last
							? cur[key] || (keys[i+1] && isNaN( keys[i+1] ) ? {} : [])
							: val;
					}

				} else {
					// Simple key, even simpler rules, since only scalars and shallow
					// arrays are allowed.

					if ($.isArray(obj[key])) {
						// val is already an array, so push on the next value.
						obj[key].push(val);

					} else if (obj[key] !== undefined) {
						// val isn't an array, but since a second value has been specified,
						// convert val into an array.
						obj[key] = [obj[key], val];

					} else {
						// val is a scalar.
						obj[key] = val;
					}
				}

			} else if (key) {
				// No value was defined, so set something meaningful.
				obj[key] = coerce
					? undefined
					: '';
			}
	});

	return obj;
}