Viewing History and Diffs

jj provides powerful tools for exploring history and comparing changes.

Viewing History

git

git log

jj log

Command comparison: git commands on the left, jj commands on the right
git	jj
git log	jj log

Log Options

git

git log --oneline

git log -n 10

git log --graph --oneline

jj log -l 10

jj log --graph

jj log --all

Command comparison: git commands on the left, jj commands on the right
git	jj
git log --oneline	jj log -l 10
git log -n 10	jj log --graph
git log --graph --oneline	jj log --all

Understanding the Log Output

In jj's log:

@ = Your working copy commit
◉ = Regular commits
◌ = Abandoned commits
@ appears in the log as the latest commit

$ jj log
@  xyzkpznx test 123
◉  prklqyso test foo
◉  roqmyuqs test bar
◉  yostqsxx qux

Viewing Commit Details

git

git show HEAD

jj show @

Command comparison: git commands on the left, jj commands on the right
git	jj
git show HEAD	jj show @

Viewing Diffs

git

git diff

git diff app.js

git diff HEAD~1 HEAD

jj diff

jj diff app.js

jj diff --from @- --to @

Command comparison: git commands on the left, jj commands on the right
git	jj
git diff	jj diff
git diff app.js	jj diff app.js
git diff HEAD~1 HEAD	jj diff --from @- --to @

Diff Syntax

jj uses --from and --to for precise diff control:

# Compare @ with parent
jj diff --from @- --to @

# Compare two commits
jj diff --from abc --to def

# Compare with main
jj diff --from main --to @

# See what changed since main
jj diff --from main

Common Diff Patterns

What changed in my working copy?

jj diff

What's different between two branches?

jj diff --from main --to feature

Show me the changes in this commit:

jj show abc
# or
jj diff --from abc^- --to abc

What files are modified?

jj status

The Status Command

git

git status

jj status

Command comparison: git commands on the left, jj commands on the right
git	jj
git status	jj status

Interactive History

jj's log is more than just text—it's an interactive history:

# View log with more details
jj log -v

# Show change IDs
jj log --change-id

# Show commit timestamps
jj log --timestamps

Comparing Files

git

git diff HEAD app.js

git diff branch1 branch2 app.js

jj diff app.js

jj diff --from branch1 --to branch2 app.js

Command comparison: git commands on the left, jj commands on the right
git	jj
git diff HEAD app.js	jj diff app.js
git diff branch1 branch2 app.js	jj diff --from branch1 --to branch2 app.js

Operations Log

jj maintains an operation log—useful for undoing:

# Show operation history
jj op log

# Output:
# 0123 minutes ago: checkout
# 0456 minutes ago: new
# 0789 minutes ago: describe

Try It Yourself

# Make some changes
echo "test" > test.txt
echo "demo" > demo.txt

# See what changed
jj diff

# Commit them
jj describe -m "Add files"
jj new

# View the commit
jj show @-

# See history
jj log

# Compare with parent
jj diff --from @- --to @

Key Takeaways

jj log shows commit history with @ marking working copy
jj diff shows @ vs parent (use --from/--to for more)
jj show displays full commit details
jj status shows pending changes
jj op log shows operation history for undo

Next Steps

Now let's explore how jj handles remote operations differently from git.