Commit message hook script to prefix Git commit messages with the Jira ticket Id taken from the current branch name

commit-msg

#!/usr/bin/env node

/**
 * Commit message hook script to prefix Git commit messages
 * with the Jira ticket Id taken from the current branch name
 * 
 * # Requirements
 * - git 2.9+ (which supports global hooks)
 * 
 * # Installation
 * - mkdir ~/.githooks
 * - git config --global core.hooksPath ~/.githooks
 * - Copy the file to ~/.githooks/commit-msg
 * - chmod +x ~/.githooks commit-msg
 */

const fs = require('fs')
const commitMessage = fs.readFileSync(process.argv[2], 'utf8')
const gitHead = fs.readFileSync('.git/HEAD', 'utf8')

// Already prefixed with Jira Ticket Id
if (/^\w+\-\d+/.test(commitMessage)) {
  return
}

// The HEAD pointer doesn't point to a JIRA ticket branch
if (!/\w+\-\d+/.test(gitHead)) {
  return
}

fs.writeFileSync(
  process.argv[2],
  `${gitHead.match(/\w+\-\d+/)[0]} ${commitMessage}`,
  'utf8'
)