Get hash of most recent git commit in Node

Question

I\'d like to get the id/hash of the most recent commit on the current branch in NodeJS.

In NodeJS, I\'d like to get the most recent id/hash, with respect to git and

Answer 1

I was inspired by edin-m's "Solution #2 (no git required)", but I didn't like the substring(5) part which felt like a dangerous assumption. I feel my RegEx is much more tolerant to the variations allowed in git's loose requirements for that file.

The following demo shows that it works for both a checked out branch and a "detached HEAD".

$ cd /tmp

$ git init githash
Initialized empty Git repository in /private/tmp/githash/.git/

$ cd githash

$ cat > githash.js <<'EOF'
const fs = require('fs');

const git_hash = () => {
    const rev = fs.readFileSync('.git/HEAD').toString().trim().split(/.*[: ]/).slice(-1)[0];
    if (rev.indexOf('/') === -1) {
        return rev;
    } else {
        return fs.readFileSync('.git/' + rev).toString().trim();
    }

}

console.log(git_hash());

EOF

$ git add githash.js

$ git commit -m 'https://stackoverflow.com/a/56975550/117471'
[master (root-commit) 164b559] https://stackoverflow.com/a/56975550/117471
 1 file changed, 14 insertions(+)
 create mode 100644 githash.js

$ node githash.js
164b559e3b93eb4c42ff21b1e9cd9774d031bb38

$ cat .git/HEAD
ref: refs/heads/master

$ git checkout 164b559e3b93eb4c42ff21b1e9cd9774d031bb38
Note: checking out '164b559e3b93eb4c42ff21b1e9cd9774d031bb38'.

You are in 'detached HEAD' state.

$ cat .git/HEAD
164b559e3b93eb4c42ff21b1e9cd9774d031bb38

$ node githash.js
164b559e3b93eb4c42ff21b1e9cd9774d031bb38