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4.1 - Intro to React and HTML

What is React?​

React is a Javascript library for building user interfaces (UI).

Take a look at this webpage. React allows you, the programmer, to build reusable components, like a sidebar, a clickable button, or a paragraph of text, which helps efficiently create interactive UI's.

Take a look at the Official React Docs.

Why React?​

  • Reusablity and Modularity:

    • React's component-based architecture, allow developers to create reusable components that manage their own state. Components are modular and can be easily maintained, tested individually, and reused. (Don't Repeat Yourself!)

  • Efficient Updates and Rendering:

    • React uses a virtual DOM to optimize updates. Instead of directly manipulating the browser's DOM, React updates a virtual representation of the DOM, which is then used to calculate the most efficient way to update the real DOM.
Deep Dive: DOM and Virtual DOM

The Document Object Model (DOM), is the data representation of a web document. representing it as nodes and objects. This way it can be modified with a scripting language such as JavaScript.

The Virtual DOM is a lightweight copy of the actual DOM. It’s a JavaScript object that React uses to keep track of changes in the UI. When a component’s state changes, React updates the virtual DOM instead of the real DOM.

How does Virtual DOM make React faster?

  1. Batching Updates: React batches multiple updates to the virtual DOM, reducing the number of times the real DOM needs to be updated.

  2. React compares the new virtual DOM to the previous virtual DOM to identify the minimal set of changes required. This process is called reconciliation.

  3. After identifying the changes, React updates only the parts of the real DOM that have changed, rather than re-rendering the entire UI. This selective rendering significantly improves performance, especially for complex UIs.

But First ... Basic HTML​

Hyper Text Markup Language (HTML):

  • Describes the structure of a webpage
  • Consists of a series of HTML elements, which label pieces of content such as "this is a heading", "this is a paragraph", "this is a link", etc.
  • For further reading check out MDN web docs tutorial-HTML
Deep Dive: Hypertext and Markdown

"Hypertext" refers to links that connect web pages to one another, either within a single website or between websites.

HTML uses "markup" to annotate text, images, and other content for display in a Web browser.

HTML markup includes special "tags" such as <head>, <title>, <body>, <footer>, <article> <p>, <div>, <img>, <ul>, <ol>, <li> and many others.

The syntax of using < and > tells the compiler that the HTML element is a tag and not actual content.

HTML Example
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>
<p>This is another paragraph.</p>

</body>
</html>

Below is a visualization of an HTML page structure: HTML Visualization

In this case, <title>Page Title</title> would be an HTML element, defined by a start tag:<title>, your content, and an end tag </title>