Client side Java script

Unit 3

Java Script: Java Script: Introduction - Client side Java script - Server side Java script - Core features – Data types and variables – Operators - Expressions and statements – Functions – Objects – Array - Date and math related objects - Document objectmodel – Event handling

Logical Operators Types of Functions

Java Script Introduction

v  JavaScript is the programming language of the web.

v  It can calculate, manipulate and validate data.

v  It can update and change both HTML and CSS.

v  JavaScript is a versatile, dynamically typed programming language that brings life to web pages by making them interactive.

v  It is used for building interactive web applications, supports both client-side and server-side development, and integrates seamlessly with HTML, CSS, and a rich standard library.

v  Object oriented

v  Platform independent

v  Update HTML Using the DOM

v  Capable of Exception handling (Exception handling is a programming technique used to manage errors or unexpected situations that occur during the execution of a program.)

v  Allows Anonymous Functions

v  (An anonymous function in JavaScript is a function without a name. Unlike named functions, these are typically used for specific tasks and are often assigned to variables, passed as arguments, or executed immediately. They are particularly useful in scenarios where the function does not need to be reused outside its immediate context)

v  JavaScript is a single-threaded language that executes one task at a time.(Single threaded processes contain the execution of instructions in a single sequence. In other words, one command is processes at a time)

v  It is an interpreted language which means it executes the code line by line.

v  The data type of the variable is decided at run-time in JavaScript, which is why it is called dynamically typed.

Why Study JavaScript?

v  JavaScript is an essential programming language for modern development due to its versatility,

v  Ease of use

v  Widespread adoption

v  It powers the majority of websites and applications, making it a critical skill for developers.

v  JavaScript enables dynamic and interactive web experiences.

v  Unlike static HTML and CSS, JavaScript allows developers to create features like animations, form validations, and real-time updates without reloading the page. (Real-time updates are information that is delivered with minimal delay, as soon as it becomes available. This is crucial for applications where immediate, up-to-date information is necessary for decision-making, such as live sports scores, stock prices, breaking news, and traffic conditions.)

v  This makes websites more engaging and user-friendly.

v  It is easy to learn and beginner-friendly, with a simple syntax that resembles natural language. JavaScript runs directly in web browsers, eliminating the need for complex setups. This accessibility makes it an excellent starting point for new programmers.

v  JavaScript is highly versatile. It can be used for front-end development with frameworks (JavaScript frameworks are collections of pre-written JavaScript code that provide a structured foundation for building and managing complex web applications.) like React and Angular, back-end development with Node.js, mobile app development using React Native, and even desktop applications with Electron.

v  It also supports advanced fields like machine learning (TensorFlow.js) and blockchain development.

v  The language has extensive community support, offering a wealth of resources, tutorials, and libraries.

v  Platforms like Stack Overflow and GitHub provide quick solutions and collaboration opportunities, making it easier to overcome challenges.

v  JavaScript offers strong career prospects.

v  It is one of the most in-demand programming languages, with opportunities in web development, mobile development, and beyond.

v  Companies like Google, Amazon, and Netflix actively seek JavaScript developers, offering competitive salaries.

v  In summary, JavaScript is indispensable for creating modern, interactive applications across various platforms.

v  Its versatility, ease of learning, and career potential make it a must-have skill for developers.

Advantages of JavaScript

1.          Saves time and bandwidth: Regardless of where you host JavaScript, it always gets executed on the client environment to save lots of bandwidth and make the execution process fast.

2.          Easily send HTTP requests: In JavaScript, XMLHttpRequest is an important object that was designed by Microsoft. The object calls made by XMLHttpRequest as an asynchronous HTTP request to the server to transfer the data to both sides without reloading the page

3.          Compatible for all browsers: The biggest advantage of JavaScript having the ability to support all modern browsers and produce an equivalent result.

4.          Community Support: Global companies support community development by creating important projects. An example is Google (created the Angular framework) or Facebook (created the React.js framework).

5.          Vastly used: JavaScript is employed everywhere on the web.

6.          Environment Support: JavaScript plays nicely with other languages and may be utilized in an enormous sort of application.

7.          Open source: Many open-source projects provide useful help for developers to add JavaScript. (Open source is software with source code that is publicly available for anyone to use, modify, and share freely.)

8.          Programming language: There are many available courses within the field of JavaScript, because of which you'll quickly and simply expand your knowledge of this programming language.

9.          Easy to use: It is not difficult to start working in JavaScript. For this reason, many of us prefer to start our adventure in the IT sector by learning this language. It gives the power to make rich interfaces.

10. Backend usage: There are some ways to use JavaScript through Node.js servers. It is possible to develop a whole JavaScript app from front to back using only JavaScript.

Disadvantages of JavaScript

1.        This may be difficult to develop large applications, although you'll also use the TypeScript overlay.

2.        This applies to larger front-end projects. The configuration is often a tedious task due to the number of tools that are required to figure together to make an environment for such a project. This is often directly associated with the library's operation.

3.        The main problem or disadvantage in JavaScript is that the code is always visible to everyone anyone can view JavaScript code.

4.        No matter what proportion fast JavaScript interprets, JavaScript DOM (Document Object Model) is slow and can be a never-fast rendering with HTML.

5.        If the error occurs in JavaScript, it can stop rendering the whole website. Browsers are extremely tolerant of JavaScript errors.                 (In JavaScript, rendering refers to the process of dynamically updating the content of a web page.)

6.        JavaScript is usually interpreted differently by different browsers. This makes it somewhat complex to read and write cross-browser code

7.        Though some HTML editors support debugging, it's not as efficient as other editors like C/C++ editors. Hence difficult for the developer to detect the matter.

8.        This continuous conversion takes longer than the conversion of a number to an integer. This increases the time needed to run the script and reduces its speed.

 

Client-side Java script

What is Client-Side Script, and how does it work?

1.          A client-side script is a tiny program (or collection of instructions) that is put into a web page. It is handled by the client browser rather than the web server.

2.          The client-side script, along with the HTML web page it is embedded in, is downloaded from the server at the client end. The code is interpreted and executed by the web browser, which then displays the results on the screen.

3.          The client refers to the script that runs on the user’s computer system. It can either be integrated (or injected) into the HTML content or stored in a separate file (known as an external script).

4.          When the script files are requested, they are transmitted from the web server (or servers) to the client system. The script is run by the client’s web browser, which subsequently displays the web page, including any visible script output.

5.          To further understand, look at the diagram below.

6.          Client-side scripts may also include instructions for the web browser to follow in response to user activities like clicking a page button. If a client wants to see the source code of a web page, they can typically look at them.

7.          Client-side Scripting Languages are widely used.

8.          Client-side scripting language or client-side programming refers to a language in which a client-side script or program is written utilizing syntax.

Client-side Java script

1.          Client-side scripting is when the server sends the code along with the HTML web page to the client. The script is referred to by the code.

2.          In other words, client-side scripting is a method for browsers to run scripts without having to connect to a server.

3.          The code runs on the client’s computer’s browser either while the web page is loading or after it has finished loading.

4.          Client-side scripting is mostly used for dynamic user interface components including pull-down menus, navigation tools, animation buttons, and data validation.

5.          It is currently quickly expanding and evolving on a daily basis. As a result, creating client-side web programming has become easier and faster, lowering server demand.

6.          By far the most popular client-side scripting languages or web scripting languages, JavaScript and jQuery are frequently utilized to construct dynamic and responsive webpages and websites.

7.          The browser downloads the code to the local machine (temporarily) and begins processing it without the server. As a result, client-side scripting is browser-specific.

The following are the most popular client-side scripting languages:

1. JavaScript is the most commonly used client-side scripting or programming language. It is written in the ECMAScript programming language.

JavaScript is a dynamically typed (also known as weakly typed) object-oriented scripting language. It uses an integrated interpreter to run directly in the browser.

Weakly typed indicates that the variables can be implicitly transformed from one data type to another.

2. VBScript: This scripting language was developed by Microsoft, based on Visual Basic. It was mostly used to improve the functionality of web pages in Internet Explorer. The Internet Explorer web browser interprets VBScript. No one really uses it now.

3. jQuery: jQuery is a JavaScript library that is fast, tiny, and lightweight. It’s used to turn a lot of JavaScript code into user-friendly functionality.

The jQuery language is used by the majority of the world’s largest firms, including Google, Microsoft, IBM, Netflix, and others.

Scripting on the client-side

Client-side scripting is a technique for enhancing the interactivity of online pages or websites. It’s mostly utilized on the front end, where the user can see what’s going on through their browser.

 

 

 

The following are some of the most common uses of client-side scripting:

1.          To get data from a user’s screen or a web browser.

2.          In the realm of online games, this term is used.

3.          To make changes to a web page without having to reload it.

4.          Validation is done using client-side scripting. If a user enters invalid credentials on the login page, the web page displays an error notice on the client machine instead of sending the information to the web server.

5.          Instead of simply displaying visuals, design ad banners that interact with the user.

6.          To make animated pictures that change as the mouse moves over them.

7.          A client-side script can be used to identify installed plug-ins and alert the user if one is needed.

The Benefits of Client-Side Scripting

The following are some of the many benefits of client-side scripting:

1.          Client-side scripting is a simple language to learn and utilize. It only necessitates rudimentary programming knowledge or experience.

2.          Client-side scripting has the advantage of being lightweight and reasonably simple to implement (syntax not too complex). The code modification and execution are both quick.

3.          Data processing is done on the client side instead of the server, making large-scale applications easier to scale. As a result, the server’s burden is reduced.

4.          Data validation on the client side can be accomplished using a client-side scripting language such as JavaScript.

5.          Client-side script execution is faster since the script is downloaded from the server and executed directly on the user’s machine via the browser.

6.          Client-side scripting can also be used for mathematical assessment.

7.          Client-side programming facilitates the completion of complex activities in a limited number of steps.

8.          Script code that is only performed by the browser and not by the server.

9.          Executing script code takes far too little time.

10. When a user taps a key, moves the mouse, or clicks, the browser responds promptly.

Client-side Scripting’s Drawbacks

The following are some of the disadvantages of client-side scripting:

1.          Client-side scripting is insecure since the code is transmitted to the client as is, and therefore visible to it if the client looks at the source code of his web page. In a nutshell, code is almost always visible.

2.          If we need to access databases or send sensitive data over the internet, client-side programming is not an option.

3.          There is no guarantee that the user’s browser has JavaScript enabled. As a result, notwithstanding the possibility of offloading, all essential functions must be loaded on the server.

4.          The script’s (or program’s) smooth operation is entirely dependent on the client’s browser, its settings, and its security level.

5.          Debugging and maintaining a web application relying on excessive JavaScript might be difficult.

6.          Client-side scripting languages are typically more constrained than server-side scripting languages in terms of capabilities.