Learn Javascript online javascript-Roadmap for beginners.

 Introduction

JavaScript is a programming language that is primarily used for front-end web development. It is often used alongside HTML and CSS to create interactive and dynamic web pages. Here are some common uses of JavaScript:

• Adding interactivity to web pages: JavaScript allows developers to add interactive elements to web pages, such as buttons, pop-up boxes, and menus.

• Creating web-based games: JavaScript can be used to create simple games that run in a web browser.

• Building web applications: JavaScript is used to create web applications, such as online calculators, chat applications, and collaborative editing tools.

• Developing browser extensions and add-ons: JavaScript is used to create extensions and add-ons for web browsers, which can enhance the functionality of the browser.

• Creating server-side applications: JavaScript can be used to create server-side applications, such as APIs and web servers.

While JavaScript is not typically used for artificial intelligence (A.I.) development, it can be used in conjunction with other technologies to create web-based A.I. applications.

Why do we learn javascript?

JavaScript is a high-level programming language that is primarily used for front-end web development. It is often used alongside HTML and CSS to create interactive and dynamic web pages. Here are some examples of what you can do with JavaScript:

• Form validation: JavaScript can be used to validate form inputs to ensure that they meet certain criteria, such as being a valid email address or a certain length.

• DOM manipulation: JavaScript can be used to manipulate the Document Object Model (DOM) of a web page, allowing you to add, remove, or modify HTML elements dynamically.

• Event handling: JavaScript can be used to handle user events, such as clicks, mouse movements, and key presses, and respond to them in real-time.

• Animation: JavaScript can be used to create animations on web pages, such as fading in and out, sliding, and rotating elements.

• API integration: JavaScript can be used to integrate with external APIs, such as social media platforms, weather services, and payment gateways, to retrieve and display data on a web page.

• Browser detection: JavaScript can be used to detect the user's browser and adjust the functionality of the web page accordingly.

• Game development: JavaScript can be used to create simple games that run in a web browser, such as Snake or Tetris.

These are just a few examples of what you can do with JavaScript. It's versatility and widespread use in web development make it an essential skill for front-end developers.

History of javascript?

JavaScript was created by Brendan Eich in just 10 days in May 1995, while he was working at Netscape Communications Corporation. Originally called Mocha, it was later renamed to LiveScript and then to JavaScript to capitalize on the popularity of Java at the time. The first version of JavaScript was released in September 1995 as part of Netscape Navigator 2.0, one of the earliest web browsers.

JavaScript quickly became popular because it allowed web developers to add interactivity and dynamic content to their web pages, which was previously not possible with static HTML. It was standardized as ECMAScript in 1997, and subsequent versions of JavaScript have been based on this standard.

Over the years, JavaScript has evolved to become a powerful and versatile programming language, capable of running on both the client side (in a web browser) and the server side (using Node.js). It is now one of the most widely used programming languages in the world, with a large and active community of developers constantly creating new libraries, frameworks, and tools to enhance its capabilities.

what is javascript?

JavaScript is a widely programming language used in web development. If you're a beginner, here are some basic concepts of JavaScript that you should learn along with examples:

• Variables: Variables are used to store data in JavaScript. You can declare a variable using the "var" keyword. Here's an example:

variable.png

• Functions: Code blocks known as functions carry out a certain duty. Using the "function" keyword, a function can be defined.
   Here's an example:

function.png

• Conditional statements: Conditional statements allow you to execute code based on a condition. You can use the "if", "else if", and "else" keywords to create conditional statements. Here's an example:

conditional.png

• Loops: Loops allow you to repeat a block of code a certain number of times. You can use the "for" loop, "while" loop, or "do-while" loop in JavaScript. Here's an example using a "for" loop:

loops.png

• Arrays: Arrays are used to store multiple values in a single variable. You can create an array using square brackets and separate the values with commas. Here's an example:

arrays.png

These are just a few basic concepts of JavaScript that you can learn as a beginner. There are many other concepts and features in JavaScript that you can explore as you become more comfortable with the language.

what are variables in javascript?

In JavaScript, variables are used to store data values. A variable is a container that holds a value, which can be a number, string, object, or any other type of data. Here is an example of declaring a variable in JavaScript:

variable-example1.png

In this example, "name" is the variable name, and "John" is the value assigned to the variable. The "var" keyword is used to declare the variable. 

Variables can also be assigned values dynamically based on user input or other factors. For example, you could prompt the user for their name and store it in a variable like this:

variable-example2.png

This will display a dialog box asking the user to enter their name, and then store the entered value in the "name" variable.

Variables can also be updated with new values as needed. For example, you could update the value of the "name" variable like this:

variable-example3.png

This would change the value of the "name" variable from "John" to "Sarah".


In JavaScript, variables are dynamically typed, which means that you don't need to specify the data type when declaring a variable. The data type is automatically determined based on the value assigned to the variable.

Here are some examples of other types of data that can be stored in variables:

variable-example4.png

These are just a few examples of how variables can be used in JavaScript. As you become more familiar with the language, you'll learn many other ways to use variables to store and manipulate data.

what is a function in javascript?

In JavaScript, a function is a block of code that performs a specific task or set of tasks. Functions can be reused throughout your code, which makes them a powerful tool for creating more efficient and readable code. Here is an example of a simple function in JavaScript:

function-example1.png

In this example, the function is named "sayHello" and it uses the "console.log" method to print the message "Hello, world!" to the console. To call the function and execute its code, you would simply write:

function-example2.png

This would invoke the "sayHello" function and cause it to print the message to the console.

Functions can also accept parameters, which are values that are passed into the function to be used in its code. Here is an example of a function that accepts a parameter:

function-example3.png

In this example, the "greet" function accepts a parameter called "name". When the function is called, a value for the "name" parameter must be passed in, like this:

function-example4.png

This would cause the function to print the message "Hello, John!" to the console. 

Functions can also return values, which are values that are computed by the function and passed back to the code that is called it. Here is an example:

function-example5.png

In this example, the "square" function accepts a parameter called "x" and returns the result of multiplying it by itself. To use the function and get its return value, you would write:

function-example6.png

This would compute the square of 5 (which is 25) and store the result in the "result" variable, which is then printed to the console.

These are just a few examples of how functions can be used in JavaScript. As you become more familiar with the language, you'll learn many other ways to use functions to organize and simplify your code.

what are conditional statements?

In JavaScript, conditional statements are used to execute different pieces of code based on whether a certain condition is true or false. Conditional statements are important because they allow you to make decisions in your code and control the flow of execution based on user input or other factors. Here are some examples of conditional statements in JavaScript:

If Statement

The "if" statement is used to execute code only if a certain condition is true. Here is an example:

if-statement.png

In this example, the code inside the "if" statement will only be executed if the "age" variable is greater than or equal to 18. If the condition is true, the message "You are an adult." will be printed on the console.

 
If-Else Statement

The "if-else" statement is used to execute one block of code if a certain condition is true, and a different block of code if the condition is false. Here is an example:

if-else statement.png

In this example, the code inside the "if" statement will be executed if the "hour" variable is less than 12, and the code inside the "else" statement will be executed if the condition is false. If the condition is true (in this case it is false because "hour" is 14), the message "Good afternoon!" will be printed to the console.

Else-If Statement

The "else-if" statement is used to execute a block of code if a certain condition is true, and if not, check another condition and execute a different block of code if that condition is true. Here is an example:

else-if statement.png

In this example, the code inside the "if" statement will be executed if the "grade" variable is greater than or equal to 90. If it is not, the code inside the first "else-if" statement will be executed if "grade" is between 80 and 89, and so on. If none of the conditions are true, the code inside the "else" statement will be executed. In this case, since "grade" is 75, the message "C" will be printed to the console.

why do we use conditional statements in javascript?

In JavaScript, conditional statements are used to control the flow of execution of a program based on certain conditions. This means that the program will execute different blocks of code depending on whether a condition is true or false.

There are many reasons why you might use conditional statements in JavaScript. Here are some examples:

1. Input Validation: Conditional statements can be used to validate user input. For example, if a user enters a value that is not within a certain range, you can use a conditional statement to display an error message.

2. Decision-Making: You can use conditional statements to make decisions in your code. For example, you might want to display a different message to a user depending on whether they are logged in or not.

3. Looping: Conditional statements can be used to control loops. For example, you might want to stop a loop from executing when a certain condition is met.

4. Event Handling: You can use conditional statements to handle events in your code. For example, you might want to display a message when a button is clicked, but only if certain conditions are met.

Overall, conditional statements are an important tool in JavaScript because they allow you to write more dynamic and interactive programs that can respond to user input and make decisions based on certain conditions.

What are loops and how many types are there?

loops are used to execute a block of code repeatedly until a certain condition is met. Loops are an important tool in programming because they allow you to perform the same task over and over again without having to write repetitive code. Here are some examples of loops in JavaScript:

For Loop

The "for" loop is used to execute a block of code a specified number of times. Here is an example:

for-loop.png

In this example, the loop will execute 5 times, starting with i=0 and increasing by 1 each time until i=4. The message "The value of i is x" will be printed to the console each time the loop executes.

While Loop

The "while" loop is used to execute a block of code as long as a certain condition is true. Here is an example:

while-loop.png

In this example, the loop will execute as long as i is less than 5. The message "The value of i is x" will be printed to the console each time the loop executes, and i will be incremented by 1 each time.

 
Do-While Loop

The "do-while" loop is similar to the "while" loop, but it will always execute the code block at least once, even if the condition is false. Here is an example:

do-while-loop.png

In this example, the code block will be executed once even though i is initially 0. After that, the loop will continue to execute as long as i is less than 5.

These are just a few examples of how loops can be used in JavaScript. As you become more familiar with the language, you'll learn many other ways to use loops to execute code repeatedly and automate tasks in your programs.

loops are an important tool in JavaScript because they allow you to write more efficient and effective code. They can save you time by allowing you to automate repetitive tasks, and they can help you avoid writing repetitive code by allowing you to iterate over arrays and perform the same operation on each element. some reasons why we use/learn loops in javascript iterating over Arrays, Data Validation, Creating Patterns, and Automating Tasks, if you want to learn about this follow Guerillateck.

what are arrays in javascript?

Arrays are used to store multiple values in a single variable. This is compared to a variable that can store only one value. Each item in an array has a number attached to it, called a numeric index, that allows you to access it. In JavaScript, arrays start at index zero and can be manipulated with various methods.

array1.png

In this example, the array "myArray" contains five values, which are the numbers 1 through 5. You can access individual values in an array by using their index number, which starts at 0. Here is an example:

array2.png

In this example, the first console.log statement accesses the first value in the array (which has an index of 0) and outputs it to the console. The second console.log statement accesses the third value in the array (which has an index of 2) and outputs it to the console.

You can also modify the values in an array by assigning new values to their index numbers. Here is an example:

array3.png

In this example, the first value in the array (which was originally 1) is changed to 10 by assigning a new value to its index number.

Arrays can also be used in conjunction with loops to perform operations on each element in the array. Here is an example:

array4.png

In this example, a "for" loop is used to iterate over each element in the array and output it to the console. The "length" property of the array is used to determine the number of elements in the array, so the loop will execute once for each element.

Overall, arrays are an important data structure in JavaScript because they allow you to store multiple values in a single variable and perform operations on them efficiently using loops and other techniques.

Some Method in Arrays?

There are many methods available for working with arrays in JavaScript. Here are some common methods that beginners can use with examples:

• push(): The push() method adds one or more elements to the end of an array. Here's an example:

push().png

In this example, the push() method is used to add the value 4 to the end of the array "myArray".

• pop(): The pop() method removes the last element from an array and returns it. Here's an example:

pop().png

In this example, the pop() method is used to remove the last element (which is 3) from the array "myArray". The removed element is stored in the variable "removedElement", and the modified array is output to the console.

• shift(): The shift() method removes the first element from an array and returns it. Here's an example:

shift().png

In this example, the shift() method is used to remove the first element (which is 1) from the array "myArray". The removed element is stored in the variable "removedElement", and the modified array is output to the console.

• unshift(): The unshift() method adds one or more elements to the beginning of an array. Here's an example:

unshift().png

In this example, the unshift() method is used to add the value 0 to the beginning of the array "myArray".

These are just a few examples of the methods available for working with arrays in JavaScript. There are many more methods and techniques that can be used to manipulate and work with arrays in JavaScript.

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Learn CSS for web development?

 

Introduction to CSS | CSS Tutorial for Beginners

what is CSS?

CSS stands for Cascading Style Sheets, and it is a style language used to describe the presentation of an HTML document. It controls the layout, colors, fonts, and other visual aspects of a web page, and it allows developers to create visually appealing websites with ease.

For beginners, CSS can seem overwhelming and confusing. However, it's important to remember that CSS is just another language, and like any language, it can be learned with practice and patience. Here are some basic concepts that beginners should be familiar with:

• Selectors: CSS selectors are used to targeting specific HTML elements and apply styles to them. Selectors can be based on element names, classes, IDs, attributes, and more.

•  Properties: CSS properties are used to define the visual style of an HTML element. Properties can control everything from font size and color to layout and positioning.

• Values: CSS values are used to set the specific value for a CSS property. Values can be in the form of keywords, numbers, or color codes.

• Box Model: The CSS Box Model is used to describe the layout and sizing of HTML elements. It consists of four parts: margin, border, padding, and content.

• Cascading and Specificity: CSS styles can be applied in a cascading manner, where multiple styles can be applied to a single HTML element, and they will be resolved based on their specificity.

• External, Internal, and Inline Styles: CSS styles can be applied in three different ways: externally through a separate CSS file, internally through the <style> tag, and inline within the HTML element using the style attribute.

Overall, CSS is an important tool for beginners to learn as it allows them to create visually appealing websites with ease. By understanding the basics of CSS and practicing regularly, beginners can become proficient in creating beautiful and functional web pages without the need for artificial intelligence.


Here is an example of a CSS rule:

css.png

In this rule, the selector is "p", which selects all the HTML <p> elements on the page, and the declarations set the text color to blue and font size to 18 pixels.

CSS is used to create responsive and mobile-friendly designs by using media queries, which allow developers to apply different styles based on the screen size or device type. This ensures that the website is optimized for different devices and provides a consistent user experience across all platforms.

In addition to basic styling, CSS also allows for more advanced features like animations, transitions, and transformations. These can be used to create dynamic and interactive web pages that engage users and enhance the overall user experience.

Overall, CSS is an essential tool for web development and allows developers to create visually appealing and user-friendly websites.

CSS History

• 1994: First Proposed by Hakon Wium Lie on 10th October
• 1996: CSS was published on 17th November with influencer Bert Bos
• Later he became co-author of the CSS
• 1996: CSS became official CSS was published in December
• 1997: Created CSS level 2 on 4th November
• 1998: Published on 12th May

CSS Comment

• Comments in CSS are used to provide notes and explanations about the code. Comments are ignored by the web browser and are only visible in the CSS file. Comments can be useful for other developers who read or modify the CSS code in the future.

• In CSS, comments are created by enclosing the text in /* and */. Here is an example of how to write a comment in CSS:

comment.png

Comments can also span multiple lines. Here is an example of a multi-line comment:

comment2.png

Comments can be used to temporarily disable a section of code without deleting it. This can be helpful when debugging or testing different styles. Here is an example of how to disable a section of code using a comment:

comment_in_css.png

In this example, the entire <p> element has been commented out, which means that the text color will not be blue.

Overall, comments in CSS are a useful tool for adding notes, explanations, and temporary disabling of code. They can help developers write cleaner, more organized code that is easier to maintain and modify in the future.

Types of CSS:

There are three types of CSS: Inline CSS, Internal CSS, and External CSS. Each type of CSS has its own benefits and drawbacks, and understanding their differences can help beginners choose the most appropriate type for their website.

• Inline CSS: Inline CSS is the most basic type of CSS and involves placing CSS styles directly within the HTML elements using the style attribute. Here is an example of how to use Inline CSS

inline-css.png

• Inline CSS is easy to implement but can be difficult to maintain and update. It also requires more code to achieve the same effect as Internal or External CSS.

• Internal CSS: Internal CSS involves placing CSS styles within the <head> section of an HTML document using the <style> tag. Here is an example of how to use Internal CSS.

internal-css.png

Internal CSS is easier to maintain than Inline CSS since all the styles are in one place. It also requires less code than Inline CSS since the styles can be applied to multiple elements at once

• External CSS: External CSS involves creating a separate CSS file and linking it to the HTML document using the <link> tag. Here is an example of how to use External CSS:

external-css.png

In this example, the CSS styles are stored in a separate file called styles.css, which can be linked to multiple HTML documents. This makes it easy to update and maintain the styles across an entire website. External CSS is also the most SEO-friendly type of CSS since it allows search engines to easily read the content of the website without having to sift through large amounts of code.

Overall, understanding the differences between Inline, Internal, and External CSS can help beginners choose the most appropriate type of CSS for their website. By using External CSS, beginners can create SEO-friendly websites that are easy to maintain and update.

What is a selector?

In CSS, selectors are used to targeting specific HTML elements on a web page and apply styles to them. Understanding selectors is essential for beginners to create effective CSS styles. Here are some common selectors in CSS with examples:

• Element Selector: The element selector targets all instances of a specific HTML element on a web page. Here is an example of how to use an element selector to style all <p> elements on a web page:

element-selector.png

• Class Selector: HTML elements having a particular class property are the focus of the class selector. To style all components with the class blue text, see the following example of how to utilize a class selector:

class-selector.png

• ID Selector: An HTML element with a specific ID attribute is the target of the ID selector. Here is an illustration of how to style a single element with the ID header using an ID selector:

id-selector.png

• Attribute Selector: The attribute selector targets HTML elements with a specific attribute value. Here is an example of how to use an attribute selector to style all elements with the type="submit" attribute:

attribute-selector.png

• Pseudo-class Selector: The pseudo-class selector targets elements based on a specific state or action. Here is an example of how to use a pseudo-class selector to style all links when they are hovered over:

pseudo-class-selector.png

When choosing a selector, it's important to consider the specificity and efficiency of the selector. Using more specific selectors will reduce the chance of unintended styling conflicts and improve the overall efficiency of the code.

Overall, understanding selectors is essential for beginners to create effective CSS styles. By using SEO-friendly selectors, beginners can create web pages that are easy to read and understand for both humans and search engines.

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CSS PRACTICE QUESTIONS?

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HTML For Bug Hunters With Examples

INTRODUCTION

The most often used markup language for constructing web pages is HTML (Hypertext Markup Language). It consists of a set of tags and attributes used to define the structure and content of a web page.

HTML documents are plain text files with the.html or.htm extension that can be opened and edited with any text editor. When you open an HTML file in a web browser, the file is read and the contents are displayed as a web page.

What is HTML

HTML (Hypertext Markup Language) is a web page creation programming language. It is made up of a collection of tags and elements that are used to structure the content on a web page.

Here is a basic HTML document example:

Boiler plate.png

The HTML document in this example begins with a <!DOCTYPE> declaration, which tells the browser what type of document it is.

This HTML document starts with  <!DOCTYPE> declaration, which specifies the HTML version used. The <html> tag encloses the entire page, whereas the <head> and <body> tags divide it into two sections. The title of the page is specified by the <title> tag in the head section.

The <h1> element is used to generate a main heading, and the <p> tag is used to construct paragraphs. There are also tags for adding photos, links, lists, tables, and other elements. HTML allows you to generate structured material that can be styled and formatted with CSS and made interactive with JavaScript.

What are HTML Attributes

HTML attributes (Hypertext Markup Language) provide additional information about HTML elements. They are inserted into an element's opening tag and consist of a name and a value.

An example of an HTML element containing attributes is as follows:

element with attributes.png

The <img> tag in this example displays an image on the web page. The src attribute specifies the image file's URL, but the alt attribute specifies the alternative text that will be displayed if the picture cannot be loaded or for accessibility reasons.

Here are some more common HTML elements and their applications:.

• href: specifies a link's URL.
• class: gives an element a class for styling purposes
• id: gives an element a unique identifier for usage with CSS or JavaScript
• style: an element's inline styles are applied.
• title: When a user hovers their cursor over an element, it displays additional information about it.

Attributes can also be applied to other HTML elements, such as the <input> tag, which has attributes such as type, name, and value and is used to construct input fields on a web page.

Common HTML elements

HTML (Hypertext Markup Language) offers many elements that can be used to organize material on a web page. Here are some of the most frequent HTML elements for beginners, along with usage examples:

•  <h1> to <h6>: used to make different-sized heads.

• <p>: used to make text paragraphs.

• <a>: used to generate hyperlinks to other websites or resources.

• <img>: used to show photos on a website.

• <ul> and <ol>: used in the creation of unordered and ordered lists.

• <table>: used to generate data tables.

These are only a few of the numerous HTML elements accessible. HTML also includes components for constructing forms, input fields, buttons, videos, audio, and other types of media.

Block-level vs inline HTML elements

Based on their usual display behavior, HTML (Hypertext Markup Language) elements are classed as either block-level or inline.

Block-level items begin on a new line and take up the entire available width, pushing any subsequent content down to the next line. They are commonly used to form larger web page layouts and divisions such as paragraphs, headings, lists, and dividers.

Here are some examples of block-level elements:

Inline elements, on the other hand, do not begin on a new line and merely take up the space required to display their information. They are frequently used to apply formatting and styling to tiny chunks of information within a block-level element.

Here are a few instances of inline elements:

Some elements, like the <image> and <input> elements, can be block-level or inline depending on how they are used.

Understanding the distinction between block-level and inline elements is critical for controlling the layout and structure of a web page using CSS (Cascading Style Sheets) and ensuring that the material is displayed in a suitable manner for its intended purpose.

How to use HTML entities

HTML (Hypertext Markup Language) entities are special codes that can be used to represent characters and symbols that are not part of the conventional ASCII character set. Entities, for example, can be used to show special characters like or — on a web page.

Here's an example of how to use HTML entities:

The "&copy;" entity in this example displays the copyright symbol. The entity is initiated by the "&" symbol and terminated by the ";" symbol.

Here are some more often-used HTML entities and their corresponding codes:

• “&amp;”: & (ampersand)
• “&lt;”: < (less than)
• “&gt;”: > (greater than)
• “&nbsp;”: non-breaking space

Entities are especially useful for showing characters that are difficult to enter or that may not be supported by all web browsers. However, it is critical to employ entities effectively and carefully in order to ensure that web pages are accessible and easy to read for all users.

Common beginner mistakes in HTML

Here are some instances of common beginning HTML (Hypertext Markup Language) errors.

• Forgetting to  close the tag

In this example, the second paragraph is missing the closing </p> tag, which can cause unexpected behavior in the layout of the page.

• Improperly nesting tags:

The "ul" tag for the sub-item should be closed before the "li" tag for the parent item in this example. Improper tag nesting can lead to layout and functionality concerns.

• Using outdated or non-standard markup:

The "center" tag is non-standard and out of date in this example, and should not be used. CSS (Cascading Style Sheets) should be used to apply styles instead.

• In-correcting using attributes:

The "alt" attribute is utilized wrongly with the "a" tag in this example. The "alt" attribute is intended to offer alternate text for images, but it should not be used for links.

By avoiding these common errors and adhering to HTML best practices, you may design web pages that are accessible, well-structured, and compatible with many devices and browsers.

How to create an HTML document

A few easy steps are required to create an HTML (Hypertext Markup Language) document. Here is an example of how to make a simple HTML document:

• Launch a plain text editor, such as Notepad or Sublime Text.

• Begin the document with the HTML doctype declaration, which informs the web browser that this is an HTML document:

• Next, create the HTML document structure by adding the <html> tags, which enclose the entire document:

• Within the <html> tags, add the <head> section, which contains metadata about the document, such as the title

• Within the <html> tags, add the <body> section, which contains the main content of the document

• Add content to the document within the <body> tags, such as headings, paragraphs, and images

• Save the file with a .html extension, such as index.html

Following these steps will allow you to generate a simple HTML document that can be read in a web browser. You may then build on this base by adding more HTML tags, formatting with CSS (Cascading Style Sheets), and adding functionality with JavaScript.

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