Saturday, 5 December 2015

Misconception about JavaScript

There are lot of misconceptions about JavaScript. Let us discuss few of them. 

JavaScript is not Java

It is very much necessary to clear that JavaScript has no relation with Java. It was initially named as LiveScript. It has been compliance with ECMAScript 5 Language Specifications. Just keep in mind, both Java and JavaScript are different animals.

JavaScript is not Just a Web Development or Client Side Tool

JavaScript is a complete programming language and it is not only used in as front end technology, it has emerged as strong candidate for future in Server Side Development i.e. Node.js.  

JavaScript is not Typeless

JavaScript is not typless, like most scripting languages, it associates type with values, not with variables. It is described as Dynamic Typing. It has six primitive data types: Boolean, Number, String, Null, Undefined and Object

JavaScript is Object Oriented Language

Most of use thing JavaScript is a structural language, but in actual it is an Object Oriented Language. Everything in JavaScript is an object and it supports both of inheritance and aggregation. It is described as Prototype Based Object Oriented Programming Language.

Browser API is not part of JavaScript

Things like Window Object, Location Object, DOM are not part of JavaScript itself, these are browser features and JavaScript just provides API to use them. These API in general called as Browser API, and they can vary from browser to browser. And this dependency is main reason to have problems to program for cross browser site development.

Block Scope

Unfortunately, JavaScript does not respect block scope for undefined variables (variables without var, they are treated as global variables). So be careful with implicit variable declaration. Furthermore, in JavaScript block scope is at function level not set of curly brackets.

JavaScript is not Context Free

In general, we consider it does not matter either a line is ended with semicolon or not, but it can cause many issues particularly in case of minification.

Validation of JavaScript

Now many IDEs provide JavaScript validation, even you can use tools/sites like JSLint with manual efforts. It’s not bad idea to use JavaScript strict mode.

Synchronous

JavaScript is basically single threaded.

this Keyword

this keyword may refer to different things with respect to context. For example, in constructor this refers to object, in simple function this refers to window .

JavaScript Custom Objects are not JSON

JavaScript Custom Objects are not JSON. JSON cannot have functions, JSON is a data interchange format.

Closures

A closure is a function having access to the parent scope, even after the parent function has closed. Closures are very interesting feature and very similar to delegates with persisted state of outer function.

Debugging

It is little tricky yet very simple to debug JavaScript code. We may discuss this topic in detail in future articles.

Context and Scope are Different things

Context and Scope are different things, in simple we can say Scope defines accessibility and life span, on other hand Context refers to what and where.

JavaScript Libraries and Frameworks

There are lot of hot topics like Jquery/ Jquery UI/ Jquery Mobile, AngularJS/Ember, Knockout JS, Kendo UI, Node JS, Lo Dash, React JS, Chart JS, Ionic and etc. these all are libraries and or frameworks developed in JavaScript. These are add-ons not the competitors.

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