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.
As of Fall 2015, the on-campus version of CS50x, CS50, was Harvard largest course. 01104671732
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.
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.
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:
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.
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).