What is JavaScript?

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The History of JavaScript 

JavaScript was developed by Brendan Eich in 1995 while he was working at Netscape. Initially intended to be called Live Script, the name was later changed. Unlike many programming languages, JavaScript does not incorporate the concepts of input or output. Instead, it functions as a scripting language within a host environment, which is responsible for providing the necessary means to interact with the external world. The most prevalent host environment for JavaScript is the web browser.



 

What is JavaScript? 

 

JavaScript, often abbreviated as JS, is a client-side programming language utilized for creating dynamic interactions in applications, games, and web development. It is regarded as one of the fundamental technologies of the web, alongside HTML and CSS. 

 

Developers employ JavaScript to enhance web pages, transforming static content into interactive experiences that respond to user actions, incorporate animations, and present real-time, variable, and personalized information.

 

JavaScript distinguishes itself from other markup languages in several significant ways.

The three core languages utilized in web design and development function collaboratively while simultaneously introducing increasing levels of complexity to a website.

 

HTML serves as a fundamental markup language, instructing the browser on how to display content to users. Its primary functions include:

•             Indicating the beginning and end of paragraphs.

•             Transforming text into headings.

•             Applying basic text styling such as bold and italics.

•             Establishing structure for spacing, indents, tables, and more.

•             Incorporating images or videos into a webpage.

 

CSS, on the other hand, is a style sheet language. This rules-based language governs how the browser applies styles to various HTML elements on a page and can also facilitate the creation of more intricate layouts, such as columns and rows.

 

In contrast, JavaScript is a scripting language designed to enhance user interaction. It enables developers to:

•             Animate images.

•             Auto play videos.

•             Generate pop-ups.

•             Respond to user actions.

•             Show dropdown menu options or links.

•             Deliver personalized content.

•             Integrate content from external websites.

•             Set cookies.

 

When a user accesses a webpage, the browser executes any scripts that are present. This dynamic code may run automatically or be triggered by user interactions.




How Does its work?

JavaScript operates through execution within a web browser, which utilizes a JavaScript engine to interpret and run the code. Below is a concise explanation of the process:

 

1. Script Loading: Upon loading a web page, the browser processes the HTML and CSS files. If it encounters a <script> tag, it retrieves the corresponding JavaScript file or code.

 

2. Code Parsing: The JavaScript engine, such as Google’s V8 in Chrome or Spider Monkey in Firefox, parses the JavaScript code. This involves reading the code and transforming it into a machine-readable format, often resulting in the creation of an Abstract Syntax Tree (AST).

 

3. Compilation: Contemporary JavaScript engines employ Just-In-Time (JIT) compilation to convert the parsed code into machine code immediately prior to execution. This approach enhances execution speed compared to line-by-line interpretation.

 

4. Code Execution: The engine executes the machine code, which includes managing the call stack—where functions are added and removed as they are invoked and return—and the heap, where objects are allocated.

 

5. Asynchronous Code Management: JavaScript effectively manages asynchronous operations through callbacks, promises, and the async/await syntax. The event loop and callback queue facilitate these operations, ensuring that the main thread remains non-blocking.

 

6.Interaction with Web APIs: JavaScript can engage with various Web APIs provided by the browser, including the Document Object Model (DOM) for HTML element manipulation, the Fetch API for network requests, among others.

 

Operators of JavaScript

JavaScript operators are symbols that facilitate the execution of operations on values and variables. The primary categories of operators in JavaScript include:

 

1. Arithmetic Operators: These are utilized for performing mathematical calculations.

   - + (Addition)

   - - (Subtraction)

   - * (Multiplication)

   - / (Division)

   - % (Modulus)

   - ++ (Increment)

   - -- (Decrement)

 

2. Assignment Operators: These operators are employed to assign values to variables.

   - = (Assignment)

   - += (Addition assignment)

   - -= (Subtraction assignment)

   - *= (Multiplication assignment)

   - /= (Division assignment)

   - %= (Modulus assignment)

 

3. Comparison Operators: These are used to compare two values.

   - == (Equal to)

   - === (Strict equal to)

   - != (Not equal to)

   - !== (Strict not equal to)

   - > (Greater than)

   - < (Less than)

   - >= (Greater than or equal to)

   - <= (Less than or equal to)

 

4. Logical Operators: These operators perform logical operations.

   - && (Logical AND)

   - || (Logical OR)

   - ! (Logical NOT)

 

5. String Operators: These are used for concatenating strings.

   - + (Concatenation)

   - += (Concatenation assignment)

 

6. Bitwise Operators: These operators conduct operations at the bit level.

   - & (AND)

   - | (OR)

   - ^ (XOR)

   - ~ (NOT)

   - << (Left shift)

   - >> (Right shift)

   - >>> (Zero-fill right shift)

 

1.       Ternary Operator:

 This serves as a concise alternative to an if-else statement.

   - condition ?

     expr1 : expr2

 

8. Type Operators: These are used to ascertain the type of a variable.

   - type of (Returns the type of a variable)

   - instance of (Determines if an object is an instance of a specific class)




 

JavaScript: A Programming Language or a Scripting Language?

 

A frequent inquiry that arises during the study of JavaScript is whether it should be categorized as a scripting language or a programming language. The technology community often engages in discussions regarding the classification of JavaScript. To better understand this discourse, it is essential to clarify the differences between scripting languages and programming languages.

 

Scripting Languages

 

Scripting languages are characterized by their interpreted nature, as opposed to being compiled. This means that they are executed line-by-line by an interpreter at runtime, facilitating faster development cycles and simpler debugging processes. These languages are typically employed for various tasks, including system administration, web development, text processing, and automation. JavaScript, in particular, is extensively utilized for client-side scripting within web browsers and has evolved into a versatile language for web development, encompassing both front-end and server-side scripting through platforms such as Node.js. Scripting languages operate within a host environment; for example, JavaScript must be embedded in HTML and subsequently interpreted by the web browser.

 

Programming Languages

 

In contrast, programming languages are generally compiled languages, meaning that the source code is transformed into machine code through a compilation process. A programming language serves as a means of communication with computers, utilizing a defined set of instructions. These languages rely on compilers and do not depend on interpretation by another language or application.

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