List files in Node that have changed between branch and main

README.md

Git diff files in Node

Useful for when you want to run a CI job only on files that have changed. Usage:

import { getChangedFiles } from './git-diff.js';

getChangedFiles('main');             // get list of diffs from "main"
getChangedFiles('[current branch]'); // get list of diffs from previous commit

⚠️ Requires git installed on the machine

git-diff.js

import { execSync } from 'child_process';

/** get an array of files that have changed between current branch and target branch */
export function getChangedFiles(targetBranch) {
  let currentBranch =
    process.env.CIRCLE_BRANCH ||
    execSync('git rev-parse --abbrev-ref HEAD').toString().trim();

  let diff =
    currentBranch === targetBranch
      ? `HEAD..HEAD~1` // if this is the targetBranch, compare previous commit to this
      : `${currentBranch}..${targetBranch}`; // otherwise compare latest-to-latest

  return execSync(`git --no-pager diff --minimal --name-only ${diff}`)
    .toString()
    .split('\n')
    .map((ln) => ln.trim())
    .filter((ln) => !!ln);
}