Getting Started with

Akshay Mathur@akshaymathu

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Ground Rules• Post on FB and Tweet now• Disturb Everyone during the

session– Not by phone rings– Not by local talks– By more information and questions

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Let’s Know Each Other

• Do you code?• OS?• Programing Language?• HTML?• Javascript?• JSON?• Why are you attending?

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Akshay Mathur

• Founding Team Member of– ShopSocially (Enabling “social” for retailers)– AirTight Neworks (Global leader of WIPS)

• 15+ years in IT industry– Currently Principal Architect at ShopSocially– Mostly worked with Startups• From Conceptualization to Stabilization• At different functions i.e. development, testing, release• With multiple technologies

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JavaScript

• Born in 1995 at Netscape• Not at all related to Java• Syntax influenced by C• Interpreted ECMA scripting lanuage• Dynamically typed• Object Oriented as well as Functional• Prototype based

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Typical Usage

• Web programing– Client side

• Web pages• Browser plugins

– Server side• SSJS (not in use)• NodeJS

• PDF documents• Desktop Widgets• MongoDB

Language Reference

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Comments

• Single line– Starts with //– Can also be used after a statement

• Multi line– Starts with /* and ends with */

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Statements

• Case sensitive• Ignore whitespace• Semicolon (;) is used as delimiter for

statements• Block of statements is delimited by curly

braces ({})

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Output

• Visible to all using DOM functionsdocument.write(‘Hello’);alert(‘How are you’);

• For developers in consoleconsole.log(“This is working”);

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Variable

• Explicitly defining is optional– JS runtime automatically defines as needed– Defining all variables with ‘var’ keyword is good

• Loosely typed– No need to define the type (int, str etc.)

• Dynamically typed– Type changes at runtime as the value changes

var my_var = ‘Hello’;my_var = 6;

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Data Types

• String: “1”, “Hello! How are you”• Number: 1, 2, 121.22• Boolean: true, false• Array: [1, “1”, false, {a: 10}]• Object: {lang: “JS”, val: my_var}• Null: null• Undefined: undefined• Functions: function(){}• Date: Mon, 23 Sep 2013 12:18:54 GMT

typeof “1” // String

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Operators

• Arithmetic+, -, *, /,%, ++, --

• Assignment=, +=, -=,*=, /=, %=

• Concatenation+

• Comparison==, ===, !=,!==, >, <,<=, >=

• Logical&&, ||, !

• Conditional() ? :

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Conditional Blocks

• If… else if … elseIf (age > 18){ can_vote = true;} else { can_vote = false;}Orcan_vote = (age>18) ? true : false;

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For Loop

• Forfor (i=0; i<array.length; i++){ console.log(array[i]);}• For/infor (item in array){ console.log(item);}

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While Loop

• Whilewhile (is_extra_water){ drain();}• Do/whiledo { drain();} while (is_extra_water);

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JS Functions

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Function

• Code block that executes on ‘call’//define the functionfunction say_hello(name){ alert(‘Hello! ‘ + name);}

//call the functionsay_hello(‘Akshay’);

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Function Arguments

• Any number of arguments can be passed without declaring

• Named arguments are not supported

say_hello(1); // Hello! 1say_hello(); // Hello! undefinedsay_hello(‘Akshay’, ‘Mathur’);

//Hello! Akshay

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Naming a Function

function my_func(){}

• A function may not have a name

function(){};

my_func = function(){};

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Variable Scope

• By default all variables are global• Variables defined with ‘var’ keyword are local to the

function• It is assumed that all variables are defined in the first

linefunction(){

var my_var = ‘Hello’;console.log(msg);var2 = 6;

}

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Return Values

• Anything can be returned from a function using return statement

function sqr(x){var sq = x * x;

return sq;}

var four_sq = sqr(4);

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Other Facts

• A function can be assigned to a variable• A function can be defined within another function• A function can return a functionfunction sqr(){ sq = function (x){

return x * x * x; }; return sq;}My_sqr = sqr(); // functionMy_sqr(3); // 27

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Global Functions• encodeURI(),

encodeURIComponent() Encodes a URI

• decodeURI(), decodeURIComponent() Decodes a URI

• escape() Encodes a string • unescape() Decodes an encoded

string

• String() Converts an object's value to a string

• Number() Converts an object's

value to a number

• isFinite() Determines whether a value is a finite, legal number

• isNaN() Determines whether a value is an illegal number

• parseInt() Parses a string and returns an integer

• parseFloat() Parses a string and returns a floating point number

• eval() Evaluates a string and executes it as if it was script code

@akshaymathu

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JS Objects

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Objects

• Everything in JS is an object (instance)“string”.length // 6“str”.length.toFixed(2) // “3.00”[‘hell’, ‘o!’].join(‘’) // ‘hello!’

• Custom objects can also be defined

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JSON

• Javascript Object has a key and a value• Key is always string• Value can be of any type– Including another JSON object

A = {key1: value1, key2: value2};or

A = new Object();A[‘key1’] = value1;A.key2 = value2;

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Object as Namespace

• It is a good practice to group variables and functions together in an object rather than keeping them global

var user = {};user.name = “Akshay”;user.greet = function(){ alert(‘Hello!‘.concat(user.name);};

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Object as Named Argument• Objects can be passed to a function as an argument• They proxy for named arguments

Say_hello = function (options){ if (typeof options === ‘Object’){ options.msg = (options.msg)?options.msg : ’Hello!’; } alert(options.msg + ‘ ‘ + options.name);}

Say_hello({name: ‘Akshay’});

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Creating Single Page Web App

Series of 3 workshopsFull Day

Hands-on

presents

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1. Simple Web Pages

• Introduction to Web and its evolution• Web page basics and HTML tags• Styling elements• JavaScript basics• Introduction to DOM• Changing style using JavaScript• Simple DOM manipulation• Responding to user actions

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2. Dynamic Web Pages

• Jquery JavaScript Framework• Handling DOM events• Getting data asynchronously via AJAX• Client side dynamism using JavaScript

templates• Simplify JS coding via CoffeeScript• Writing JS classes (prototypes)

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3. Single Page App

• Understanding MVC concepts• Introduction BackboneJS and UnderscoreJS• Using Backbone models, views and router• Dealing with collections• Custom events and their handlers• Adjusting URLs for making browser buttons

work

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Document Object Model

• Window Object– Represents the browser window– All Javascript functions and variable are attached

here by default• Document Object– Represents the page rendered inside the window– All HTML elements are available here• In the hierarchy they are attached

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Manipulating the Web Page

• Get programmatic handle of an HTML element via Document Object Model (DOM)

var el = document.getElementByID(‘a_unique_id’);

• Change desired property of the elementel.src = “my_photo.png”

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JS Framework

• Library for simplifying JS coding– Jquery is most popular

• Provides simple interface and syntactic sugar for common JS work– Selecting DOM element– DOM traversal and manipulation– Event handling

• Takes care of cross browser and cross version issues

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Jquery

• Takes care of cross browser and cross version issues• Library for simplifying JS coding– Everything is via functions– Same function for get and set

• Provides simple interface and syntactic sugar for common JS work– Selecting DOM element– DOM traversal and manipulation– Event handling

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Javascript Templates

• Dynamically creates HTML code in JS– Data driven HTML– Allows variable substitution, looping and

conditional statements• Generated HTML is inserted into the DOM for

changing part of the page on-the-fly

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Using Template

<script type="text/x-jquery-tmpl” id=”photo">

<img src=“${photo_url}” title="${name}" />

</script>

<script type="text/javascript”>template = $(’#photo').template();t_html = $.tmpl(template, data);$(“#container”).html(t_html);

</script>

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AJAX

• A way in web browser to communicate with server without reloading the page

• XmlHttpRequest (XHR) object can also create HTTP request and receive response– The request happens asynchronously• Other operations on page are allowed during the

request

– Received data does not render automatically• Data needs to be received in a callback function and

used programmatically

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AJAX Call$.ajax({

url: ‘/my_ajax_target’,type: ‘POST’,DataType: ‘json’,data: {id: 2},success: function(response){

alert(‘Hello! ‘ + response.name);},

error: function(){alert(‘Please try later’);}

});

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CoffeeScript

• A language with simple syntax– No semicolons and braces– Resembles to English– Indentation decides the code blocks

• Compiles into Javascript– Provides syntactic sugar for boilerplate code• Manage variable scope• Class instead of prototype

– Generates good quality, error free code

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Cofeescript to Javascript

greet_me = (name) ->greeting_word = 'Hello!'alert "#{greeting_word} #{name}”

Compiles to

greet_me = function(name) { var greeting_word; greeting_word = 'Hello!'; return alert("" + greeting_word

+ " " + name); };

@akshaymathu

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BackboneJS

• Provides MVC structure for Javascript– The model object holds data– The view object handles visual elements and

interactions– The controller object glues everything together and

provides communication amongst objects• Custom Events help writing good code and

eliminates use of global variables– The event object allows raising and handling custom

events

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BackboneJS code in Coffeescriptclass LoginModel extends Backbone.Modelclass LoginView extends Backbone.View

initialize: =>@template = $(’#login_template').template()@render()

render: =>$(@el).html $.tmpl(@template, @model.toJSON())

events:'click #login_btn' : ’login_handler’

login_handler: (ev) =>window.mpq_track ’Login Click’

class LoginController extends Backbone.Routerinitialize: =>

@l_model = new LoginModel window.app_info@l_view = new LoginView model: model, el:

’#login_div’

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Thanks

@akshaymathu

http://www.quora.com/Akshay-Mathur