CS 511-Web Engineering
Week 5
Topic 60-62
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| CS 511-Week 5:Topic 60-62 |
Topic 60:
Navigations in Bootstrap:
n Bootstrap, the navigation component is used to create responsive navigation bars. It utilizes various HTML elements to implement navigation, including unordered lists, list items, and links. Here's how navigation can be implemented using these elements:
1. Unordered List: To start building a navigation bar, you can use the <ul> element with the class "nav" to create an unordered list.
Example: <ul class="nav">
2. List Items: Each item in the navigation bar is represented by a list item (<li>) with the class "nav-item".
Example: <li class="nav-item">
3 .Links: To create interactive navigation elements, you can add links (<a>) within the list items. Apply the class "nav-link" to style the links accordingly.
Example: <a class="nav-link" href="#">Link</a>
4. Dropdown using Nested Unordered List: Bootstrap allows you to create dropdown menus within the navigation bar. This can be achieved by using a nested unordered list structure.
a) Parent <li>: To create a dropdown parent item, add the class "nav-item dropdown" to the list item.
Example: <li class="nav-item dropdown">
b) Parent <a>: Add the class "nav-link dropdown-toggle" to the parent link element. Also, include the "data-bs-toggle" attribute with the value "dropdown" to enable the dropdown functionality.
Example: <a class="nav-link dropdown-toggle" data-bs-toggle="dropdown" href="#">Dropdown</a>
c) Nested <ul>: Inside the parent list item, create a nested unordered list (<ul>) with the class "dropdown-menu". This will contain the dropdown menu items.
Example: <ul class="dropdown-menu">
d) List Item: Within the nested unordered list, create list items (<li>) to represent the individual dropdown menu items.
Example: <li><a class="dropdown-item" href="#">Dropdown Item</a></li>
By utilizing these HTML elements and their respective classes, you can easily create navigation bars and incorporate dropdown menus within them using Bootstrap's navigation component.
Please note that the examples provided are for illustrative purposes, and you can customize them further to fit your specific design and content requirements.
Topic 61:
Introduction to JavaScript: JavaScript's Evolution:
JavaScript was initially introduced by Netscape in their Navigator browser in 1996. Over the years, JavaScript has evolved and become one of the most popular programming languages for web development. It has undergone significant changes and improvements, both in terms of language features and its role in contemporary software development.
Historical Versions and ECMAScript Specification:
The JavaScript supported by web browsers includes language features that are not necessarily part of the current ECMAScript specification. Additionally, certain language features are missing from that specification. The commonly used version of ECMAScript is the Sixth Edition (ES6), which introduced many new features and enhancements. However, JavaScript continues to evolve, with the release of the 12th edition (ECMAScript 2021) in 2021, bringing further improvements and new capabilities to the language.
JavaScript and Web 2.0:
In the early days, JavaScript had limited applications and was mainly used for simple tasks such as form validation and basic interactivity on web pages. However, with the emergence of Web 2.0 in the 2000s, JavaScript started to play a more significant role in creating dynamic and interactive web experiences. One of the key technologies that contributed to this shift was AJAX (Asynchronous JavaScript and XML), which allowed web applications to retrieve data from servers without requiring a page reload. AJAX became both an acronym and a general term to describe this approach, and JavaScript played a crucial role in enabling this functionality.
JavaScript in Contemporary Software Development:
In contemporary software development, JavaScript has become a versatile and powerful programming language that is not limited to web browsers alone. With the advent of server-side JavaScript frameworks such as Node.js, JavaScript can now be used to develop full-stack web applications, server-side APIs, and even desktop or mobile applications. JavaScript is also extensively used in frameworks and libraries like React, Angular, and Vue.js for building complex user interfaces and managing application states.
The JavaScript ecosystem has grown tremendously, with a vast array of libraries, frameworks, and tools available to developers. This vibrant ecosystem, along with the continuous improvements to the language itself, has made JavaScript a preferred choice for building modern, interactive, and scalable software applications.
In summary, JavaScript has come a long way since its introduction in the mid-1990s. It has evolved into a powerful and widely adopted programming language that enables developers to create dynamic web experiences, build full-stack applications, and contribute to the ever-expanding world of software development.
Topic 62:
Variables in JavaScript:
In programming languages, variables can be categorized into two types: dynamic and static. In languages like C, C++, and Java, variables are statically typed, meaning their types are determined and declared during compile-time.
However, JavaScript takes a different approach by being dynamically typed, along with languages like Python. This dynamic typing allows for more flexibility in variable declarations, as we don't need to explicitly specify the type using familiar keywords like int, char, or String. Instead, to declare a variable in JavaScript, we use the var keyword, followed by the variable name and a semicolon.
Data Types in JavaScript:
JavaScript has two types of data: reference data types and primitive data types. Reference data types include objects, and when assigning a value to a variable of a reference data type, the variable stores the memory address where the object is stored. This means that the variable essentially points to the object in memory.
On the other hand, primitive data types in JavaScript store the exact value of the variable. Examples of primitive data types include Boolean, number, and string. When assigning a value to a variable of a primitive data type, the actual value is stored directly in the variable.
In summary, JavaScript's dynamic typing allows for more flexibility in variable declarations, as the type of a variable is determined at runtime. JavaScript also distinguishes between reference data types, where variables store the memory address of objects, and primitive data types, where variables store the actual value. Understanding these concepts is important when working with variables and data in JavaScript.
Assessment:
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Which type of variables are determined and declared during compile-time?
a) Dynamic variables
b) Static variables
c) Primitive variables
d) Reference variables
Answer: b) Static variables
JavaScript variables are dynamically typed. What does this mean?
a) The type of a variable can change during runtime.
b) The type of a variable is determined at compile-time.
c) The type of a variable is fixed and cannot be changed.
Answer: a) The type of a variable can change during runtime.
In JavaScript, reference data types store the:
a) Exact value of the variable
b) Memory address of the object
c) Type information of the variable
d) None of the above
Answer: b) Memory address of the object
What happens if you declare a variable without using the var keyword in JavaScript?
a) The variable will be treated as a global variable.
b) The variable will be automatically assigned a value of undefined.
c) None of the above.
Answer: a) The variable will be treated as a global variable.
Which data type is used to represent text in JavaScript?
a) Number
b) Boolean
c) String
d) Object
THE END 😊
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