IMAGINATION vs KNOWLEDGE...the war is on !!!

Sunday, April 10, 2016

Internationalization Using jquery.i18n.properties.js

Internationalization refers to automatically showing localized text in application pages for users visiting the site from different regions in the world or localizing the site content based on the language preference chosen by the user.

Getting jquery.i18n.properties.js

First of all we need to download the plugin.

The plugin can be downloaded from https://github.com/jquery-i18n-properties/jquery-i18n-properties.

A minified version of the same is available at http://code.google.com/p/jquery-i18n-properties/downloads/list

Steps For Internationalization

The first step as with all JavaScript libraries is to include the JavaScript into HTML. Jquery.i18n.properties.js is a jQuery plugin; hence we need to include jQuery also into HTML before jquery.i18n.properties.js like shown below:

<HEAD>
        <script type="text/javascript" src="js/jquery-1.10.2.js"></script>
        <script type="text/javascript" src="js/jquery.i18n.properties.js"></script>
</HEAD>

The sample HTML is given below:

<BODY>
        <h2>Internationalization using jQuery.i18n.properties</h2>
        <div id="langBox">
            Language:
            <select id="lang">
                <option value="en" selected>en</option>
                <option value="tr">tr</option>
                <option value="fr">fr</option>
            </select>
        </div>
        <div id="lWelcome">Welcome to My Site!</div><br>
        <div id="lSelLang">Your Selected Language is: en </div>
</BODY>

The jquery.i18n.properties.js plugin consumes .properties files for doing text translations. The sample of properties file is mentioned below:

Messages_fr.properties
lWelcome = Bienvenue sur le site de démonstration !
lSelLang = Votre langue sélectionnée est : {0}

Messages.properties
lWelcome = Welcome to my Site!
lSelLang = Your Selected Language is: {0}

Messages_tr.properties
lWelcome = Benim Sitemize Hoşgeldiniz !
lSelLang = Sizin Seçili Dil geçerli: {0}

Loading localized strings from .properties

The below code sample is used to load the resource bundle properties file using jquery.i18n.properties.js

$(function() {  
  $.i18n.properties({ 
    name: 'Messages', 
    path: 'bundle/', 
    mode: 'both', 
    language: lang, 
    callback: function() { 
      $("#lWelcome").text($.i18n.prop('lWelcome')); 
      $("#lSelLang").text($.i18n.prop('lSelLang', lang)); 
    }
  });
});

Advantages of jquery.i18n.properties.js

The main advantage of this plugin is that it uses .properties files for internationalization. This is helpful as same properties files could be shared with other parts of the program.

The support of parameterization of strings is also beneficial as this enables one to have complex multilingual strings.

Has option to use map as well as JavaScript variables/functions for retrieving translated strings.

The plugin is very lightweight and can be easily used with any HTML as it is jQuery based.

Wednesday, April 16, 2014

JavaScript for Application: OO and Best Practices

So, here are some of our best javascript practices:

1) Almost always scope your JS code "immediate function"

JavaScript does not have code block scoping (with { ... }) but everything in a function is scoped. Consequently, when building a new module, always create an immediate function to scope all the properties and functions. This way, you can expose the public properties and methods/object types you want, and keep the rest visible only to this function body (this is very convenient for scoping).

// create the mymodule object if it does not already exists

// Note: this is global scope since it is outside of the immediate function

var mymodule = mymodule || {};

//immediate function notation(start with ";" to make it semicolumn-less friendly)
;(function(){

// obviously, always have "var ..." when defining a variable (always)

var foo;

// nobody outside can see this var

function bar();

// this will be visible outside, since attached to mymodule.

mymodule.publicFun1 = function() {...}; })();

// execute the function immediately

Partition your code diligently with this technic to ease later refactoring. Do not hesitate to have multiple "immediate function block" in the same javascript file, the more atomic your code is, the more manageable it will become. Use clear commenting style to separate your different sections.

2) Object Type the JS Way with prototype

Here is the prototype way to create an Object Type.

// try to always scope your API, Object Types, properties in a namespace
var mymodule = mymodule || {};;(function(){// Constructorfunction Person(name){this._name = name;
// as convention, ._*** is for privates properties
// Note: there is a more robust way to do do private, but this will be for later
}
// A ObjectType Method
Person.prototype.name = function(name){
// Note: here, we use the js/jQuery style, setter/getter in one method
if (typeof name === "undefined"){
return this._name ;
}else{
this._name = name;
}}
// expose the Person "Object Type" in the mymodule namespace mymodule.Person = Person;})();
// ... somewhere else in your js or page code
// create an instance of this Object Type
var person1 = new mymodule.Person("Animesh");
// get some properties
console.log("person name: " + person1.name());
// >>> will output >>> "Animesh"

3) "Classical" Inheritance in JS

Here are 5 lines of code that you can add to your application, or use from some librairies (e.g., YUI, Brite, ...) to do a pseudo class inheritance with JavaScript. This is a very simple and convenient way to bring "classical" inheritance in JS.

function inherit(Child, Parent) {
var F = function() {};
F.prototype = Parent.prototype;
Child.prototype = new F();
Child._super = Parent.prototype;
Child.prototype.constructor = Child;
};
var mymodule = mymodule || {};
;(function() {
function Person(name) {
this._name = name;
}

Person.prototype.name = function(name) {
if( typeof name === "undefined") { return this._name; }
else { this._name = name; }
}

Person.prototype.canCode = function(canCode) {
if( typeof canCode === "undefined") {
return this._canCode || false;
} else {
this._canCode = canCode;
}
}

function Programmer(name,language) {
Programmer._super.constructor.call(this, name); this.canCode(true); this.language(language);
}
// inherit Programmer with Person, call this after the Programmer constructor

inherit(Programmer, Person);
Programmer.prototype.language = function(language) {
// sort version of the if/else
return (typeof language === "undefined")? this._language:this._language = language;
}

// Note: Here you could override or overwrite person methods with // Programmer.prototype.****

mymodule.Person = Person; mymodule.Programmer = Programmer; })(); // in the application code
var a = new mymodule.Person("Animesh");
var b = new mymodule.Programmer("Nanda","js");
console.log(a.constructor.name + " " + a.name() + " can code: " + a.canCode());
console.log(b.constructor.name + " " + b.name() + " can code: " + b.canCode() + " language: " + b.language());

4) Private Methods

The immediate function code block and the javascript function methods function.call and function.apply are perfect to create private methods. Immediate function code block is also a great way to make utility functions, constants, default values, and cache visible only to a module or sub module.

With Regards,
Animesh Nanda
Sr.Software Engineer | Photon Infotech
Bengaluru | Karnataka | INDIA.

Sunday, March 23, 2014

Basic Javascript Technical Interview Questions and Answers for Web Developers

1. What is JavaScript?

JavaScript is a platform-independent,event-driven, interpreted client-side scripting language developed by Netscape Communications Corp. and Sun Microsystems.

JavaScript is a general-purpose programming language designed to let programmers of all skill levels control the behavior of software objects. The language is used most widely today in Web browsers whose software objects tend to represent a variety of HTML elements in a document and the document itself.

But the language is used with other kinds of objects in other environments. For example, Adobe Acrobat Forms uses JavaScript as its underlying scripting language to glue together objects that are unique to the forms generated by Adobe Acrobat.

Therefore, it is important to distinguish JavaScript, the language, from the objects it can communicate with in any particular environment.

When used for Web documents, the scripts go directly inside the HTML documents and are downloaded to the browser with the rest of the HTML tags and content.

2. How is JavaScript different from Java?

Don't be fooled by the term Java in both. Both are quite different technologies.

JavaScript was developed by Brendan Eich of Netscape; Java was developed at Sun Microsystems. While the two languages share some common syntax, they were developed independently of each other and for different audiences. Java is a full-fledged programming language tailored for network computing; it includes hundreds of its own objects, including objects for creating user interfaces that appear in Java applets (in Web browsers) or standalone Java applications. In contrast, JavaScript relies on whatever environment it's operating in for the user interface, such as a Web document's form elements.

JavaScript was initially called LiveScript at Netscape while it was under development. A licensing deal between Netscape and Sun at the last minute let Netscape plug the "Java" name into the name of its scripting language. Programmers use entirely different tools for Java and JavaScript. It is also not uncommon for a programmer of one language to be ignorant of the other. The two languages don't rely on each other and are intended for different purposes. In some ways, the "Java" name on JavaScript has confused the world's understanding of the differences between the two. On the other hand, JavaScript is much easier to learn than Java and can offer a gentle introduction for newcomers who want to graduate to Java and the kinds of applications you can develop with it.

3. What is the official JavaScript website?

This is a trick question used by interviewers to evaluate the candidate’s knowledge of JavaScript. Most people will simply say javascript.com is the official website.

The truth is- there is no official website for Javascript you can refer to. It was developed by Brendan Eich for Netscape. It was based on the ECMAScript language standard; ECMA-262 being the official JavaScript standard.

4. What’s relationship between JavaScript and ECMAScript?

ECMAScript is yet another name for JavaScript (other names include LiveScript). The current JavaScript that you see supported in browsers is ECMAScript revision 3.

5. What are the various datatypes in javascript?

Number
String
Boolean
Function
Object
Null
Undefined

6. What boolean operators does JavaScript support?

&&, || and !

7. What is negative infinity?

It’s a number in JavaScript, derived by dividing negative number by zero.

8. Is it possible to check if a variable is an object?

Yes, it is possible to do so. The following piece of code will help achieve the same.

if(abc && typeof abc === "object") {
console.log('abc is an object and does not return null value');
}

9. Can you explain what isNaN function does?

isNaN function will check an argument and return TRUE (1) if the argument does not seem to be a number.

10. How do you convert numbers between different bases in JavaScript?

Use the parseInt() function, that takes a string as the first parameter, and the base as a second parameter. So to convert hexadecimal 3F to decimal, use parseInt ("3F", 16);

11. What is the difference between undefined value and null value?

undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value.

Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.

Unassigned variables are initialized by JavaScript with a default value of undefined. JavaScript never sets a value to null. That must be done programmatically.

12. What is the difference between “==” and “===”?

While “==” checks only for equality, “===” checks for equality as well as the type.

13. Differentiate between “var a=2” and “a =2”

The major difference between the two is that one variable is local and the other is global. “var” basically defines the scope of the variable.

When we add var to a variable value assignment, javascript ensures that the variable is confined to whichever function it is assigned to and does not collide with the same name variable within another function.

When we don’t use var, then it is declared as a global function and chances of collision can happen. So it’s always advisable to use “var” before variable value assignment. If needed use an anonymous function for closure.

14. What is Javascript namespacing? How and where is it used?

Using global variables in Javascript is evil and a bad practice. That being said, namespacing is used to bundle up all your functionality using a unique name. In JavaScript, a namespace is really just an object that you’ve attached all further methods, properties and objects. It promotes modularity and code reuse in the application.

15. What does "1"+2+4 evaluate to?

Since 1 is a string, everything is a string, so the result is 124.

16. How about 2+5+"8"?

Since 2 and 5 are integers, this is number arithmetic, since 8 is a string, it’s concatenation, so 78 is the result.

17. How to create arrays in JavaScript?

We can declare an array like this
var scripts = new Array();
We can add elements to this array like this

scripts[0] = "PHP";
scripts[1] = "ASP";
scripts[2] = "JavaScript";
scripts[3] = "HTML";

Now our array scrips has 4 elements inside it and we can print or access them by using their index number. Note that index number starts from 0. To get the third element of the array we have to use the index number 2 . Here is the way to get the third element of an array.
document.write(scripts[2]);
We also can create an array like this
var no_array = new Array(21, 22, 23, 24, 25);

18. How do you create a new object in JavaScript?

var obj = new Object(); or var obj = {};

19. How do you assign object properties?

obj["age"] = 17 or obj.age = 17

20. What’s a way to append a value to an array?

arr[arr.length] = value;

21. What is this keyword?

It refers to the current object.

22. How many looping structures can you find in javascript?

If you are a programmer, you know the use of loops. It is used to run a piece of code multiple times according to some particular condition. Javascript being a popular scripting language supports the following loops

for
while
do-while loop

23. Are javascript and jQuery different?

jQuery is a quick as well as concise JavaScript Library that simplifies HTML document traversing, animating, event handling, & Ajax interactions for the purpose of quick web development needs. So although they are not entirely different, both are not the same either!

24. Explain the strict mode in Javascript.

The strict mode ensures that if functions are not properly thought it, those are disabled. It also kept a check on potentially unsafe actions and throw errors when it happens.

25. Is it possible for you to write a one line JavaScript code that concatenates all strings passed into a function?

The following function should help in producing the desired result

function concatenate()
{
return String.prototype.concat.apply('', arguments);
}

26. Explain Javascript closures.

A basic overview of javascript closures is that it is a stack-frame which is not de-allocated when the function returns.

27. What is event bubbling?

Event bubbling describes the behavior of events in child and parent nodes in the Document Object Model (DOM); that is, all child node events are automatically passed to its parent nodes. The benefit of this method is speed, because the code only needs to traverse the DOM tree once. This is useful when you want to place more than one event listener on a DOM element since you can put just one listener on all of the elements, thus code simplicity and reduction. One application of this is the creation of one event listener on a page’s body element to respond to any click event that occurs within the page’s body.

28. Difference between window.onload and onDocumentReady?

The onload event does not fire until every last piece of the page is loaded, this includes css and images, which means there’s a huge delay before any code is executed.

That isnt what we want. We just want to wait until the DOM is loaded and is able to be manipulated. onDocumentReady allows the programmer to do that.

29. How do you change the style/class on any element?

document.getElementById(“myText”).style.fontSize = “20″;
-or-
document.getElementById(“myText”).className = “anyclass”;

30. How is form submission possible via javascript?

We can achieve the desired form submission by using the function document.forms[0].submit().

It must be noted that the 0 in the piece of code given above refers to the form index. Say we have multiple forms on a particular page. To make all the form procession unique, we give each form index numbers. The first form will have the index number as 0. The second form will have an incremented number, 1. The third will have 2 and so on.

31. How JavaScript timers work? What is a drawback of JavaScript timers?

Timers allow you to execute code at a set time or repeatedly using an interval. This is accomplished with the setTimeout, setInterval, and clearInterval functions. The setTimeout(function, delay) function initiates a timer that calls a specific function after the delay; it returns an id value that can be used to access it later. The setInterval(function, delay) function is similar to the setTimeout function except that it executes repeatedly on the delay and only stops when cancelled. The clearInterval(id) function is used to stop a timer. Timers can be tricky to use since they operate within a single thread, thus events queue up waiting to execute.

32. How to get CheckBox status whether it is checked or not?

alert(document.getElementById('checkbox1').checked);

if it will be checked you will get true else false.

33. How to get value from a textbox?

alert(document.getElementById('txtbox1').value);

34. How to get value from dropdown (select) control?

alert(document.getElementById('dropdown1').value);

35. How to get value from RadioButtonList control?

Here id is the name property of the RadioButtonList

function GetRadioButtonValue(id)

{

var radio = document.getElementsByName(id);

for (var ii = 0; ii < radio.length; ii++)

{

if (radio[ii].checked)

alert(radio[ii].value);

}

36. How to detect the operating system on the client machine?

In order to detect the operating system on the client machine, the navigator.appVersion
string (property) should be used.

With Regards,
Animesh Nanda
Sr.Software Engineer | Photon Infotech
Bengaluru | Karnataka | INDIA.