Introduction to Javascript

• In JavaScript, to declare a new variable, we can use the keywords: var, let, and const
• Variable names are used to identify and store data in JavaScript
• There are different data types in JavaScript that include primitive data types
• JavaScript is a front-end scripting language developed by Netscape for dynamic content
• JavaScript is lightweight, but with limited capabilities
• JavaScript can be used as an object-oriented language
• JavaScript is a client-side technology
• JavaScript is embedded in your HTML page and interpreted by the Web browser
• Client-side JavaScript is the language's most common format
• Client-side JavaScript implies that HTML can incorporate client-interacting programs, control the browser, and make the content of the HTML powerful
• JavaScript was initially named "LiveScript" and later changed to "JavaScript" to position it as the "younger brother" of Java
• JavaScript was submitted for standardization to the ECMA world organization
• The standardized language is known as ECMAScript
• JavaScript is supported by major browsers like Firefox, Chrome, Internet Explorer, Safari, and Opera
• Advantages of JavaScript:
• Less contact with the server allows for validating user feedback before sending the page to the server
• Immediate feedback to visitors without the need for page reloads
• Expanded interactivity for creating responsive web page interfaces
• Greater interfacing capabilities for richer GUI on web pages
• Limitations of JavaScript:
• JavaScript cannot read or write files
• JavaScript lacks support for organizing applications
• JavaScript runs in a single execution thread
• How to use JavaScript in your web page:
• JavaScript codes run from inside a web page using the <script> element
• Scripts can be embedded or placed in an external file and connected to a page like CSS
• External <script> elements use the src attribute to point to a script file with a .js suffix
• Benefits of using external style sheets for JavaScript:
• Allows the application of the same script to different websites
• Each external script requires an additional server HTTP request, which can slow down performance
• Variables in JavaScript are also known as holders or containers
• Variables allow you to position data and refer to the data by naming the container
• Variables can be known as something that may change
• In JavaScript, variables can hold various data values
• To declare a new variable in JavaScript, keywords var, let, and const are used
• Using var keyword
• var keyword is used to create and declare a variable
• Variables can be declared without initializing or initialized with a number using var
• Using let
• let variables are declared similarly to var but impose scope constraints