Introduction 路 Bootstrap 知识图谱

Introduction 路 Bootstrap

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Introduction 路 Bootstrap
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Important globals
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Introduction
Get started with Bootstrap, the world鈥檚 most popular framework for building responsive, mobile-first sites, with jsDelivr and a template starter page.
Quick start
Looking to quickly add Bootstrap to your project? Use jsDelivr, provided for free by the folks at jsDelivr. Using a package manager or need to download the source files? Head to the downloads page.
CSS
Copy-paste the stylesheet <link> into your <head> before all other stylesheets to load our CSS.
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.2.1/dist/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
JS
Many of our components require the use of JavaScript to function. Specifically, they require jQuery, Popper.js, and our own JavaScript plugins. Place the following <script>s near the end of your pages, right before the closing </body> tag, to enable them. jQuery must come first, then Popper.js, and then our JavaScript plugins.
We use jQuery鈥檚 slim build, but the full version is also supported.
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.14.6/dist/umd/popper.min.js" integrity="sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.2.1/dist/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
Curious which components explicitly require jQuery, our JS, and Popper.js? Click the show components link below. If you鈥檙e at all unsure about the general page structure, keep reading for an example page template.
Our bootstrap.bundle.js and bootstrap.bundle.min.js include Popper, but not jQuery. For more information about what鈥檚 included in Bootstrap, please see our contents section.
Show components requiring JavaScript
Alerts for dismissing
Buttons for toggling states and checkbox/radio functionality
Carousel for all slide behaviors, controls, and indicators
Collapse for toggling visibility of content
Dropdowns for displaying and positioning (also requires Popper.js)
Modals for displaying, positioning, and scroll behavior
Navbar for extending our Collapse plugin to implement responsive behavior
Tooltips and popovers for displaying and positioning (also requires Popper.js)
Scrollspy for scroll behavior and navigation updates
Starter template
Be sure to have your pages set up with the latest design and development standards. That means using an HTML5 doctype and including a viewport meta tag for proper responsive behaviors. Put it all together and your pages should look like this:
<!doctype html>
<html lang="en">
<head>

<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.2.1/dist/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
<title>Hello, world!</title>
</head>
<body>
<h1>Hello, world!</h1>


<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.14.6/dist/umd/popper.min.js" integrity="sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.2.1/dist/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
</body>
</html>
That鈥檚 all you need for overall page requirements. Visit the Layout docs or our official examples to start laying out your site鈥檚 content and components.
Important globals
Bootstrap employs a handful of important global styles and settings that you鈥檒l need to be aware of when using it, all of which are almost exclusively geared towards the normalization of cross browser styles. Let鈥檚 dive in.
HTML5 doctype
Bootstrap requires the use of the HTML5 doctype. Without it, you鈥檒l see some funky incomplete styling, but including it shouldn鈥檛 cause any considerable hiccups.
<!doctype html>
<html lang="en">
...
</html>
Responsive meta tag
Bootstrap is developed mobile first, a strategy in which we optimize code for mobile devices first and then scale up components as necessary using CSS media queries. To ensure proper rendering and touch zooming for all devices, add the responsive viewport meta tag to your <head>.
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
You can see an example of this in action in the starter template.
Box-sizing
For more straightforward sizing in CSS, we switch the global box-sizing value from content-box to border-box. This ensures padding does not affect the final computed width of an element, but it can cause problems with some third party software like Google Maps and Google Custom Search Engine.
On the rare occasion you need to override it, use something like the following:
.selector-for-some-widget {
box-sizing: content-box;
With the above snippet, nested elements鈥攊ncluding generated content via ::before and ::after鈥攚ill all inherit the specified box-sizing for that .selector-for-some-widget.
Learn more about box model and sizing at CSS Tricks.
Reboot
For improved cross-browser rendering, we use Reboot to correct inconsistencies across browsers and devices while providing slightly more opinionated resets to common HTML elements.
Community
Stay up to date on the development of Bootstrap and reach out to the community with these helpful resources.
Follow @getbootstrap on Twitter.
Read and subscribe to The Official Bootstrap Blog.
Chat with fellow Bootstrappers in IRC. On the irc.freenode.net server, in the ##bootstrap channel.
Implementation help may be found at Stack Overflow (tagged bootstrap-4).
Developers should use the keyword bootstrap on packages which modify or add to the functionality of Bootstrap when distributing through npm or similar delivery mechanisms for maximum discoverability.
You can also follow @getbootstrap on Twitter for the latest gossip and awesome music videos.