DS dsathyakumar

The following summarises the learnings of migrating from the async promises module to ES6 promises, with a simple sample.

Async is a library containing a bunch of async utility functions like

####The example had a combo of both:

	// The Binary tree will be built with the Tree Node representation (Linked representation)
	function TreeNode(val) {
	this.val = val;
	this.left = this.right = null;
	}

	// Convert a given array of data values into a binary tree representation
	// This assumes a 0 index array
	// So for an index i, the Left Child would be at 2(i) + 1
	// The right Child will be at 2(i) + 2

	// Post Order traversal => Left - Right - Data
	// L-R-D
	// Possible combinations
	// 1. L-D
	// Only Left exists. Right is absent. Since the Node has to be processed after the
	// LEFT is processed, its pushed into the stack for later processing.
	// Continue process the LEFT subtree.
	// 2. R-D
	// Only Right exists. Left is absent. Since the Node has to be processed after the
	// RIGHT is processed, its pushed into the stack for later processing.


	// A pre-order traversal means Data - LEFT - RIGHT
	// So, the possible combinations are
	// 1. D-L
	// No Right => Process Node and proceed with Left SubTree
	// No need to push into a stack for later processing (as there is no RIGHT)
	// 2. D-R
	// No Left => Process Node and proceed with Right SubTree.
	// No need to push into a stack for later processing (as RIGHT exists)
	// and RIGHT is being processed currently (due to absence of a LEFT)

	// inOrder Traversal
	// Left - Data - Right

	// Note that the Data is processed only after LEFT is processed.
	// Same way, Right is processed only after Left and Data are processed.
	// So, the key here is, the moment a LEFT occurs, push it into the stack for later
	// processing.
	// So, when a Node is popped off the stack, its not guaranteed to have a RIGHT.
	// So, when we hit a LEAF node, we pop the immediate previous ancestor, but,
	// This is not guaranteed to have a RIGHT. Just process it.



	const UploaderMachine = Machine(
	{
	strict: true,
	id: "uploader-machine",
	context: {
	progress: false,
	progressDataModel: {
	progressMsg: "",

	require('marko/node-require').install();
	const http = require('http');
	const server = require('http').createServer();
	const port = 8080;
	const indexTemplate = require('./index.marko');
	server.on('request', (req, res) => {
	indexTemplate.render({
	name: 'Frank',
	count: 30,
	colors: ['red', 'green', 'blue']

	{
	"name": "marko3-http",
	"version": "0.0.0",
	"description": "Example of using Marko with a simple Node.js HTTP server",
	"main": "server.js",
	"scripts": {
	"test": "echo \"Error: no test specified\" && exit 1"
	},
	"keywords": [
	"marko",

	<html>
	<head></head>
	<body>
	<p>Hello ${data.name}! You have ${data.count} messages!</p>
	<ul if(data.colors && data.colors.length)>
	<li style="color: ${color}" for(color in data.colors)>${color}</li>
	</ul>
	<include("./footer.marko") name=data.name/>
	</body>
	</html>