dig.js

/**
    * Uses map syntax to retrieve the given object, or return null if any
    * portion of the chain is null or undefined. The chain should be given with one
    * field or method per argument. Methods will be called with the previous step as
    * `this` and no arguments; this can be used for many string and array methods, as
    * well as getters from various libraries.
    *
    * For example, given the object `foo = {bar: function (x) { return x+3; }};`, then
    * `objectDig(foo, "bar.toExponential", [[2], [1]])` would return "5.0e+0".
    *
    * @param   {Object}    b   The base object to work from.
    * @param   {String}    h   The chain of fields/methods to access, seperated by dots
    *      (eg, "foo.bar"). Any links in this chain may be prefixed with '!' to be not-ed
    *      while resolving.
    * @param   {Array} a An array containing arguments to any methods in the chain.
    *      Each method, when found, will be called with the then-head of this array, and the
    *      array moved to the next element. Null may be given to call a method without
    *      arguments, otherwise each function found in the chain will be passed one element
    *      from this array. This must be an array of arrays (standard `apply` semantics).
    * @param   {Object}    df  The default value. If any link in the chain is missing or
    *      no chain is given and `b` is undefined, this will be returned.
    *
    * @returns The last link in the given chain, or `df` if the chain could not be completed.
    */
	function objectDig(b, h, a, df) {
		if (typeof b == "undefined" || !h) {
			return b;
		}

		var l = h.split('.'), c = _.clone(a || []), ll = l.length;
		df = df || null;

		for (var i = 0; i < ll; ++i) {
			if (_.isUndefined(b) || _.isNull(b)) {
				return df;
			}

			var li = l[i], f = false;
			if (li[0] == '!') {
				f = true;
				li = li.substr(1);
			}

			var d = b[li];
			if (_.isFunction(d)) {
				d = d.apply(b, _.first(c) || []);
				c = c ? _.rest(c) : null;
			}

			b = f ? !d : d;
		}

		if (_.isUndefined(b)) {
			b = df;
		}

		return b;
	}