Oves Enterprise

JavaScript

“Nobody expected this, but JavaScript
has become the world’s most important
programming language today”
—Douglas Crockford

What is Javascript?

JavaScript is a simple and easy-to-learn programming language as compared to other languages such as C++, Ruby, and Python. It is a high-level, interpreted language that can easily be embedded with languages like HTML. It was developed by Netscape Communications Corporation, Mozilla Foundation, and ECMA International. Brendan Eich is known as the creator or designer of the JavaScript programming language.

Some amazing features of JavaScript are as follows:

  • Lightweight, interpreted language.
  • Easily embedded with languages like HTML, CSS, and Java.
  • Also works as a client-side scripting language, which helps in creating dynamic web pages.

Discover our expertises

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The differences between Java and JavaScript?


Java is a complete programming language. In contrast, JavaScript is a coded program that can be introduced to HTML pages. These two languages are not at all inter-dependent and are designed for the different intent. Java is an object - oriented programming (OOPS) or structured programming language like C++ or C whereas JavaScript is a client-side scripting language.

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JavaScript Types and Data Literals;

    JavaScript has three primitive data types: string, number and boolean, and we can test if a variable v holds a value of such a type with the help of typeof(v) as, for instance, in typeof(v)==="number".

    There are five basic reference types: Object, Array, Function, Date and RegExp. Arrays, functions, dates and regular expressions are special types of objects, but, conceptually, dates and regular expressions are primitive data values, and happen to be implemented in the form of wrapper objects.

    The types of variables, array elements, function parameters and return values are not declared and are normally not checked by JavaScript engines. Type conversion (casting) is performed automatically.

    The value of a variable may be.

    A data value: either a string, a number, or a boolean;

    An object reference: either referencing an ordinary object, or an array, function, date, or regular expression;

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What are JavaScript Data Types?

    Following are the JavaScript Data types:

  • Number
  • String
  • Boolean
  • Object
  • Undefined
What are undeclared and undefined variables?

Undeclared variables are those that do not exist in a program and are not declared. If the program tries to read the value of an undeclared variable, then a runtime error is encountered.

Undefined variables are those that are declared in the program but have not been given any value. If the program tries to read the value of an undefined variable, an undefined value is returned.

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Four Important Types of Data Structures

    In summary, the four iportant types of data structures supported by JavaScript are:


  • array lists, such as ["one","two","three"], which are special JS objects called 'arrays', but since they are dynamic, they are rather array lists as defined in the Java programming language.

  • records, which are special JS objects, such as {firstName:"Tom", lastName:"Smith"}, as discussed above

  • maps, which are also special JS objects, such as {"one":1, "two":2, "three":3}, as discussed above

  • entity tables, like for instance the Table 2 shown below, which are special maps where the values are entity records with a standard ID (or primary key) slot, such that the keys of the map are the standard IDs of these entity records.

JavaScript Example

JavaScript Frameworks

  • ReactJS
  • AngularJS
  • NodeJS
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ReactJS

The main idea behind ReactJS development was to find a framework that helps in building a dynamic library with high performance. A suitable example of this was to provide newsfeeds at the same time when people are chatting. Optimization of the development process and bringing on JavaScript was all that was required at that time. ReactJS is more like an open-source JavaScript library rather than a framework. Used for building amazing user interfaces, it is good for rendering performance.

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AngularJS

Launched in 2009 by Google, AngularJS is an open source client-side web framework. It assists AngularJS developers to resolve issues in single page web application containing a shell page with multiple views. It gels up well with all other libraries and thus helps in extending HTML vocabulary for your web application. AngularJS Development works on the features like routing, data binding, templates, dependency injection, directives, deep linking, and filters.

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NodeJS

Node.js is a open source, server-side platform built on Google Chrome’s JavaScript Engine. The number of websites using NodeJS has crossed 84,000. It is one of the most downloaded, cross-platform runtime environments for executing JavaScript code.

  • Node.js is an open source server environment
  • Node.js runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
  • Node.js uses JavaScript on the server

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