017-git-branching.md

Git Branches

So far, we have been working only on our Main branch, which is created by default when creating a new GitHub repository. In this chapter, you will learn more about Git Branches. Why you need them and how to work with them.

The official definition of a Git branch from the git-scm.com website is the following:

A branch in Git is simply a lightweight movable pointer to one of these commits.

This might be a bit confusing in case that you are just getting started. So you could think of branches as a way to work on your project by adding a new feature of bug fixes without affecting the Main branch.

That way, each new feature or bug fix that you are developing could live on a separate branch, and later on, once you are ready and have fully tested the changes, you can merge the new branch to your main branch. You will learn more about merging in the next chapter!

If we look into the following illustration where we have a few branches, you can see that it looks like a tree, hence the term branching:

Thanks to the multiple branches, you can have multiple people working on different features or fixes at the same time each one working on their own branch.

The image shows 3 branches:

• The main branch
• New Branch 1
• New Branch 2

The main branch is the default branch that you are already familiar with. We can consider the other two branches as two new features that are being developed. One developer could be working on a new contact form for your web application on branch #1, and another developer could be working on a user registration form feature on branch #2.

Thanks to the separate branches, both developers can work on the same project without getting into each others way.

Next, let's go ahead and learn how to create new branches and see this in action!

Creating a new branch

Let's start by creating a new branch called newFeature. In order to create the branch, you could use the following command:

git branch newFeature

Now, in order to switch to that new branch, you would need to run the following command:

git checkout newFeature

Note: You can use the git checkout command to switch between different branches.

The above two commands could be combined into 1, so that you don't have to create the branch first and then switch to the new branch. You could use this command instead, which would do both:

git checkout -b newFeature

Once you run this command, you will see the following output:

Switched to a new branch 'newFeature'

In order to check what branch you are currently on, you can use the following command:

git branch

Output:

  main
* newFeature

We can tell that we have 2 branches: the main one and the newFeature one that we just created. The star before the newFeature branch name indicates that we are currently on the newFeature branch.

If you were to use the git checkout command to switch to the main branch:

git checkout main

And then run git branch again. You will see the following output indicating that you are now on the main branch:

* main
  newFeature

Making changes to the new branch

Now let's go ahead and make a change on the new feature branch. First switch to the branch with the git checkout command:

git checkout newFeature

Note: we only need to add the -b argument when creating new branches

Check that you've actually switched to the correct branch:

git branch

Output:

  main
* newFeature

Now let's create a new file with some demo content. You can do that with the following command:

echo "<h1>My First Feature Branch</h1>" > feature1.html

The above will echo out the <h1>My First Feature Branch</h1> string and store it in a new file called feature1.html.

After that, stage the file and commit the change:

git add feature1.html
git commit -m "Add feature1.html"

The new feature1.html file will only be present on the newFeature branch. If you were to switch to the main branch and run the ls command or check the git log, you will be able to see that the file is not there.

You can check that by using the git log command:

git log

With that, we've used quite a bit of the commands that we've covered in the previous chapters!

Compare branches

You can also compare two branches with the following commands.

• Shows the commits on branchA that are not on branchB:

git log BranchA..BranchB

• Shows the difference of what is in branchA but not in branchB:

git diff BranchB...BranchA

Renaming a branch

In case that you've created a branch with the wrong name or if you think that the name could be improved as it is not descriptive enough, you can rename a branch by running the following command:

git branch -m wrong-branch-name correct-branch-name

If you want to rename your current branch, you could just run the following:

git branch -m my-branch-name

After that, if you run git branch again you will be able to see the correct branch name.

Deleting a branch

If you wanted to completely delete a specific branch you could run the following command:

git branch -d name_of_the_branch

This would only delete the branch from your local repository, in case that you've already pushed the branch to GitHub, you can use the following command to delete the remote branch:

git push origin --delete name_of_the_branch

If you wanted to synchronize your local branches with the remote branches you could run the following command:

git fetch

Conclusion

With that, our newFeature branch is now ahead of the main branch with 1 commit. So in order to get that new changes over to the main branch, we need to merge the newFeature branch into our main branch.

In the next chapter, you will learn how to merge your changes from one branch to another!

One thing that you might want to keep in mind is that in the past when creating a new GitHub repository the default branch name was called master. However, new repositories created on GitHub use main instead of master as the default branch name. This is part of GitHub's effort to remove unnecessary references to slavery and replace them with more inclusive terms.