Git repo stats

git-stats.js

/**
 * Hosted at: https://gist.github.com/ericyd/c36ff66a40c3b7ede7ac9dd95ae260af
 * Usage:
 *   cd my-local-git-repo
 *   curl https://gist.githubusercontent.com/ericyd/c36ff66a40c3b7ede7ac9dd95ae260af/raw/git-stats.js > git-stats.js
 *   node git-stats.js
 */

const { exec } = require('child_process')
const { promisify } = require('util')

const execAsync = promisify(exec)

const ignoredFilePatterns = [
  /\.json$/,
  /\.yaml$/,
  /\.yml$/,
  /\.d\.ts$/,
  /\.md$/,
  /\.graphql$/,
  /__generated__/,
]

// https://git-scm.com/docs/pretty-formats
const authorFormat = {
  email: 'ae',
  name: 'an',
  committerName: 'cn',
  committerEmail: 'ce',
}

async function main() {
  // shows logs in descending order
  const logs = await execute(
    `git log --date=local --pretty=format:'%h,%${authorFormat.email}'`
  )
  const lines = logs.split('\n')

  // how many commits in your repo?
  console.log({
    'total commit count': lines.length,
    first5: lines
      .map((head0) => head0.split(','))
      .map(([a]) => a)
      .slice(0, 5),
  })

  const grouped = await Promise.all(lines.map(processLine))

  const contributions = grouped
    .filter(Boolean)
    .reduce((all, { author, additions, deletions }) => {
      if (author in all) {
        all[author] = {
          additions: all[author].additions + additions,
          deletions: all[author].deletions + deletions,
          commits: all[author].commits + 1,
        }
      } else {
        all[author] = {
          additions,
          deletions,
          commits: 1,
        }
      }
      return all
    }, {})

  console.log('\n')
  printFormattedContributors(contributions)
}

async function processLine(head0, i, lines) {
  process.stdout.write('.')
  // since we're mapping through the array, we have to be more defensive about accessing elements in the array.
  if (i + 1 >= lines.length) {
    return null
  }
  const head1 = lines[i + 1]
  const [sha0, author] = head0.split(',')
  const [sha1] = head1.split(',')
  const diff = await execute(`git diff --numstat ${sha1} ${sha0}`)

  return diff.split('\n').reduce(
    (totals, file) => {
      if (file.trim() === '') {
        return totals
      }
      const [added, deleted, filename] = file.split('\t')
      if (ignoredFilePatterns.some((regex) => filename.match(regex))) {
        return totals
      }

      // binary files will come through as "-"
      if (!Number.isNaN(parseInt(added))) {
        totals.additions += parseInt(added)
      }

      if (!Number.isNaN(parseInt(deleted))) {
        totals.deletions += parseInt(deleted)
      }

      return totals
    },
    { author, additions: 0, deletions: 0 }
  )
}

function printFormattedContributors(contributions) {
  const contributors = Object.entries(contributions).reduce(
    (all, [author, values]) => [...all, { author, ...values }],
    []
  )
  // sorted by additions | deletions | commits | author
  const sorted = contributors.sort(sortBy('additions'))
  const longestAuthor = Math.max(
    ...Object.keys(contributions).map((a) => a.length)
  )
  console.log(
    `${'author'.padEnd(longestAuthor, ' ')} | additions | deletions | commits`
  )
  console.log(
    `${'-'.padEnd(longestAuthor, '-')} | --------- | --------- | -------`
  )

  sorted
    .map(({ author, additions, deletions, commits }) =>
      [
        author.padEnd(longestAuthor, ' '),
        additions.toString().padEnd('additions'.length, ' '),
        deletions.toString().padEnd('deletions'.length, ' '),
        commits,
      ].join(' | ')
    )
    .forEach((line) => console.log(line))
}

async function execute(command) {
  const { stdout, stderr } = await execAsync(command)
  if (stderr !== '') {
    throw new Error(stderr)
  }
  return stdout
}

function sortBy(key) {
  return (a, b) => (a[key] > b[key] ? -1 : a[key] < b[key] ? 1 : 0)
}

main()

Might require Node 16+

cd my-local-git-repo
curl https://gist.githubusercontent.com/ericyd/c36ff66a40c3b7ede7ac9dd95ae260af/raw/git-stats.js > git-stats.js
node git-stats.js

Consider adding option to analyze PRs. I believe this requires network connectivity so might not be ideal

git ls-remote origin 'pull/*/head'

Or investigate shortlog command, e.g.

git shortlog -n 
git shortlog -s -n