What is SVG?

SVG stands for Scalable Vector Graphics
SVG is used to define graphics for the Web
SVG is a W3C recommendation
The HTML svg Element
The HTML svg element is a container for SVG graphics.
SVG has several methods for drawing paths, boxes, circles, text, and graphic images.


This is CS50x, Harvard University introduction to the intellectual enterprises of computer science and the art of programming for majors and non-majors alike, with or without prior programming experience.
An entry-level course taught by David J. Malan, CS50x teaches students how to think algorithmically and solve problems efficiently. Topics include abstraction, algorithms, data structures, encapsulation, resource management, security, software engineering, and web development. Languages include C, PHP, and JavaScript plus SQL, CSS, and HTML. Problem sets inspired by real-world domains of biology, cryptography, finance, forensics, and gaming.
As of Fall 2015, the on-campus version of CS50x, CS50, was Harvard largest course. 01104671732

Background Images

Different Images for Different Devices
A large image can be perfect on a big computer screen, but useless on a small device. Why load a large image when you have to scale it down anyway? To reduce the load, or for any other reasons, you can use media queries to display different images on different devices.


Screen readers

Use screen reader utilities to hide elements on all devices except screen readers.

Components and Props

Components let you split the UI into independent, reusable pieces, and think about each piece in isolation. This page provides an introduction to the idea of components. You can find a detailed component API reference here.
Conceptually, components are like JavaScript functions. They accept arbitrary inputs (called “props”) and return React elements describing what should appear on the screen. 01104671732

State and Lifecycle

This page introduces the concept of state and lifecycle in a React component. You can find a detailed component API reference here.
Consider the ticking clock example from one of the previous sections. In Rendering Elements, we have only learned one way to update the UI. We call ReactDOM.render() to change the rendered output:


Related Content


Alerts Provide contextual feedback messages for typical user actions with the handful of available and flexible alert messages.


Migrating to v4 Bootstrap 4 is a major rewrite of the entire project. The most notable changes are summarized below, followed by more specific changes to relevant components.


Tooltips Documentation and examples for adding custom Bootstrap tooltips with CSS and JavaScript using CSS3 for animations and data-attributes for local title storage.


The Viewport What is The Viewport?
The viewport is the user visible area of a web page.
The viewport varies with the device, and will be smaller on a mobile phone than on a computer screen.
Before tablets and mobile phones, web pages were designed only for computer screens, and it was common for web pages to have a static design and a fixed size.
Then, when we started surfing the internet using tablets and mobile phones, fixed size web pages were too large to fit the viewport.
To fix this, browsers on those devices scaled down the entire web page to fit the screen. This was not perfect!! But a quick fix.


Text/Typography Bootstrap 4 uses a default font-size of 16px, and its line-height is 1.5.
The default font-family is "Helvetica Neue", Helvetica, Arial, sans-serif.
In addition, all p elements have margin-top: 0 and margin-bottom: 1rem (16px by default).


Icons Guidance and suggestions for using external icon libraries with Bootstrap.