Javascript method delayed chaining

API.js

// var test = new API("Router.svc");
// test.get().top(5).view("map");
// It should execute() only when the last function has been called.

var API = function (webservice) {
	this.webservice(webservice);
	return this;
};

API.prototype = {
	version: function (urlFormat) {
		if (urlFormat) {
			return "v" + urlFormat.split('.').join('_');
		}
		return sessionStorage.getItem("version");
	},
	path: function () {
		return "../WebAPI/";
	},
	execute: function () {
		var path = this.path() + this.webservice() + ".svc/";
		if (this.__parameters) {
			path += "?";
		}
		var first = true;
		for (var k in this.__parameters) {
			if (k !== "type")
			path += ((first) ? (function(){first = false; return ""})() : "&") + "$" + k + "=" + this.__parameters[k];
		};
		console.log(this.__parameters.type + ": " + path);
		return this;
	},
	put: function () {
		this.doIt("type","put");
		return this;
	},
	post: function () {
		this.doIt("type","post");
		return this;
	},
	get: function() {
		this.doIt("type","get");
		return this;
	},
	delete: function() {
		this.doIt("type","delete");
		return this;
	},
	toString: function () {
		return "API";
	},
	webservice: function(webservice) {
		if (webservice) {
			this.__webservice = webservice;
		}
		else {
			return this.__webservice;
		}
	},
	top: function (p) {
		this.doIt("top",p);
		return this;
	},
	view: function (p) {
		this.doIt("view",p);
		return this;
	},
	orderby: function (p) {
		this.doIt("orderby",p);
		return this;
	},
	criteria: function (p) {
		this.doIt("criteria",p);
		return this;
	},
	skip: function (p) {
		this.doIt("skip",p);
		return this;
	},
	filter: function (p) {
		this.doIt("filter",p);
		return this;
	},
	doIt: function (method, parameter) {
		this.__timerStop();
		// this.__parameters.push(JSON.parse('{"'+method+'":"'+parameter+'"}'));
		this.__parameters[method] = parameter;
		this.__timerStart();
	},
	__timerStop: function () {
		if (this.__timer) {
			clearTimeout(this.__timer);
		}
	},
	__timerStart: function (append) {
		var self = this;
		if (this.__timer) {
			this.__timerStop();
		}
		this.__timer = setTimeout(function() {
			console.log("executing.");
			console.log(JSON.stringify(self.__parameters));
			self.execute();
		}, 25);
	},
	__parameters: {}
};