书名：Bootstrap 4 Cookbook
作者名：Ajdin Imsirovic
本章字数：529字
更新时间：2021-07-02 21:07:59

How to do it...

Install bower using npm:

      npm install -g bower

Verify the bower installation:

      which bower && bower -v

Note that both commands should return some values.

Install Bootstrap 4 alpha 5 (this is not a typo!):

      bower install bootstrap#v4.0.0-alpha.5

We are installing an older version on purpose. This will be explained in the next steps.

See the list of the installed dependencies:

      bower list

The preceding command will print out the status of your project's dependencies, including the available update to the currently installed Bootstrap 4 alpha 5.

Initialize git in root:

      cd && cd workspace;
git init

Stage the files into git's staging area:

      git add --all

Commit the changes with a message:

      git commit -m “Add B4, alpha 5”

Upgrade Bootstrap 4 to alpha 6 with bower:

      bower install bootstrap#v4.0.0-alpha.6

To install this update, Windows users will have to use the command prompt (rather than Git Bash for Windows).

When prompted for answer, type "2" and then press ENTER.

Now, using git diff, we have at our fingertips the full view of changes that happened between alpha 5 and alpha 6 versions of Bootstrap 4. However, it is not feasible to simply use a blanket git diff command because too many changes are made to too many files between each version. A much better strategy is to use the git diff --stat, with the --stat flag giving us a nice overall idea of the changes, as well as which files had the most changes and which had the least. The following screenshot lists only the beginning of the output of the git diff --stat command, and does not include all the files affected, but it gives us a nice visual overview of changes made between alpha versions 5 and 6:

For Windows users, before listing the result of the git diff --stat command, Windows command prompt will throw a bunch of errors--just use the Page Down button to move past them.

Now we can inspect only the files that we are interested in, for example, the following command:

      git diff bower_components/bootstrap/scss/_alert.scss

The preceding command will show us the changes made only in the _alert.scss partial, between Bootstrap 4 Alpha 5 and Alpha 6 versions. In the following screenshot, we can see one of the changes made to this file:

With this approach, it is also really simple to track the changes to the _alert.scss file in the previous versions of Bootstrap 4 alpha. For example, we can downgrade our Bootstrap 4 installation with the help of Bower, and then repeat our git diff for the _alert.scss file only, by running the following commands:

      bower install bootstrap#4.0.0-alpha.4
      git diff bower_components/bootstrap/scss/_alert.scss

With this recipe, we are able to have complete, fine-grained control of observing the changes made to the framework through its versions. This is an amazing approach to understand the changes that occurred to specific components between different versions of the framework. It can help us understand why bugs occurred in our code, avoid pitfalls when working with legacy code, and learn the approaches taken by the Bootstrap contributors and how to better work with Sass in Bootstrap.