Lesson 2.5.2: Messages

A commit message is read by someone who wasn't there. With a shared format, it makes sense at a glance.

The idea

A commit message is read by someone who wasn't there: you, three months from now, or whoever works with you. It has to say what changes, in a format everyone reads the same way.

The most widely used format is called Conventional Commits:

type(scope): short summary

- detail 1
- detail 2

The structure

Part	What it is	Example
`type`	What kind of change it is. Always there	`feat`
`(scope)`	Which part of the project it touches. Optional	`(table)`
`: summary`	What the change does, in one short line	`: let the user choose the table's number`
Body	The details, as bullets, after a blank line. Optional	`- the table(n) function writes any table`

The scope isn't the branch: it's the part of the project that changes, like table, game or page.

The types

Type	When
`feat`	Something new: a function, a page
`fix`	Fixing a bug
`docs`	Documentation only
`style`	Formatting: spaces, indentation, commas. The code does the same
`refactor`	Reorganising code without changing what it does
`test`	Adding or changing tests
`chore`	Maintenance: configuration, dependencies

There are more (perf, build, ci), but these cover almost everything.

The rules

Short summary: about 50 characters, no full stop.
Lowercase, saying what it does: "add", not "added" or "adding".
One commit, one change: if the summary needs "and", it's probably two commits.

Writing a message with a body

-m is for one line. For a message with details, it's better to write it in VS Code. Once:

Terminal

$ git config --global core.editor "code --wait"

On macOS, first, in VS Code: Cmd + Shift + P → Shell Command: Install 'code' command in PATH.

From then on, git commit without -m opens the message in VS Code:

Terminal

$ git commit

Write it, save and close the tab: the commit happens when you close it.

feat(table): let the user choose the table's number

- the table(n) function writes the table for any number
- table.js calls it with 3, as before

This is how it looks in the history:

Terminal

$ git log -1

Terminal

commit 66c4396a81db05aa5bc2940c0f5b6a6642b44c9b (HEAD -> main)
Author: Ana García <ana@example.com>
Date:   Tue Oct 20 18:30:00 2026 +0200

    feat(table): let the user choose the table's number

    - the table(n) function writes the table for any number
    - table.js calls it with 3, as before

From here on, the course's commits follow this format.

Try it

Exercise

Write the message for each change:

table.js stopped at 9 and you fix it so it reaches 10.
You rename the variable i to number so it reads better. The program does the same.
You add a goodbye to hello.js.

Show the solution

fix(table): reach 10
refactor(table): rename i to number
feat(greeting): add the goodbye

One message per commit: that's three commits, not one.

Summary

type(scope): summary, and if needed, details as bullets after a blank line.
The type says what kind of change it is: feat, fix, refactor…
The scope is the part of the project, not the branch.
Short summary, lowercase, saying what it does. One commit, one change.