We also have another option to include Bootstrap in our project by the use of CDN or the Content Delivery Network. Using this we can get the Bootstrap files on-the-fly on the users machine and render the website accordingy. Different URLs are there to obtain only CSS or only JS or the complete package. The URLs are as follows:
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
JS, Popper and JQuery:
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>
The attributes integrity and crossorigin have been added to Bootstrap CDN to implement Subresource Integrity (SRI). It is a security feature that enables to mitigate the risk of attacks originating from compromised CDNs, by ensuring that the files our website fetches (from a CDN or anywhere) have been delivered without unexpected manipulation. It works by allowing us to provide a cryptographic hash that a fetched file must match.
Once the compiled Bootstrap is downloaded, unzip the compressed folder to see the structure. We'll find the following file structure and contents.
bootstrap/ |—— css/ | |—— bootstrap.css | |—— bootstrap.min.css | |—— bootstrap-theme.css | |—— bootstrap-theme.min.css |—— js/ | |—— bootstrap.js | |—— bootstrap.min.js |—— fonts/ | |—— glyphicons-halflings-regular.eot | |—— glyphicons-halflings-regular.svg | |—— glyphicons-halflings-regular.ttf | |—— glyphicons-halflings-regular.woff
The compiled version of Bootstrap provides compiled CSS and JS files (bootstrap.*), as well as compiled and minified CSS and JS (bootstrap.min.*).