Callback Function

Read more details about Callback Function from the following web site:

Couple of lines from the above site "A callback function, also known as a higher-order function, is a function that is passed to another function (let's call this other function "otherFunction") as a parameter, and the callback function is called (or executed) inside the otherFunction."

Read more...

http://javascriptissexy.com/understand-javascript-callback-functions-and-use-them/

Promises

"Jo vaadaa kiya voo nibhana padegaa"

How people explain things in simple words so that many others can understand? I am really thankful to Sandeep Panda for explaining JavaScript Promises in simple English!

Couple of lines from this site "If you use the Promise API to make an asynchronous call to a remote web service you will create a Promise object which represents the data that will be returned by the web service in future...".

Read more...

http://www.sitepoint.com/overview-javascript-promises/

https://pouchdb.com/2015/05/18/we-have-a-problem-with-promises.html

module.exports in Node.js

Suppose you want to write a module, say a functions module and access it in another module, say main.js, how are you going to do it in Node.js?

Real simple!

Create two .js files under C:\nodetest folder: functions.js, main.js

functions.js
module.exports = { addNumbers : function() { var total = 0; for (var a = 0; a < arguments.length; a++){ total += parseInt(arguments[a]); } return total; }, findArea : function(r){ return 3.142 * r * r; } };

or 

functions.js:
this.addNumbers = function() { var total = 0; for (var a = 0; a < arguments.length; a++){ total += parseInt(arguments[a]); } return total; }; this.findArea = function(r){ return 3.142 * r * r; };

main.js
var functions = require('./functions.js'); console.log(functions.addNumbers(1,2)); console.log(functions.findArea(2));

Run the main.js from command prompt!

C:\nodetest>node main

Reference:

http://www.sitepoint.com/understanding-module-exports-exports-node-js/

Using NodeJS, express, and MongoDB

Using NodeJS, express, and MongoDB stack? The following web site gives an introduction about how to install and run a full stack using these technologies in easy steps. Cool!
http://cwbuecheler.com/web/tutorials/2013/node-express-mongo/

Predefined JavaScript function methods: apply(), call()

I was searching online to find a way to explain JavaScript predefined function methods: apply() and call(). This site http://hangar.runway7.net/javascript/difference-call-apply explains in simple English. Thanks a bunch!

Sample Ajax using jQuery & PHP

I started searching for a simple example that covers "PHP, jQuery, Ajax" and I found this web site which is simple and awesome: http://brian.staruk.me/php/2013/sample-jquery-php-ajax-script/. Thanks to Brian Staurk!

Things to learn if you want to learn Web Development

1. Responsive Web Design - Things that you need to focus on:

• Media queries - for example: <link rel="stylesheet" type="text/css" media="screen and (max-device-width: 480px)" href="style480.css" />
• Viewport meta tag - controls the dimensions of the mobile browser window
• Flexible layout - Use percentages and third-party flexible grids
• Flexible images - set max-width style for image as 100%; myimage { max-width: 100%;}

2. Cascade Style Sheets

• inline styles, internal styles and external styles
• id, class, element selectors and specificity
• CSS positioning and display properties
• Building navigation bars using CSS
• Background images, sprites
• Building simple grids
• Playing with page CSS using Chrome developer tools, Firebug in Fire fox
• CSS3 features

3. JavaScript

• Capturing the DOM elements
• Functions - creating and calling
• Variables - globals, locals, hoisting
• Loops and Conditionals
• Form validations
• Event binding and delegation, Event capturing and bubbling
• Objects and constructor functions
• AJAX

4. HTML Elements

• Form elements
• Layout elements
• Special elements
• Web Storage, Local Storage
• HTML 4.01 and HTML 5