ghist.js

var history = [];
try{
  history = require(process.cwd()+'/.git/past-branches.json');
}
catch(err) {}

var now = Date.now();

var second = 1000;
var minute = 60 * second;
var hour = minute * 60;
var day = hour * 24;

history.forEach(function(row) {
  var change = now - row[1];
  if(change > day) {
    console.log('*', row[0], 'last checked out', Math.floor(change/day), 'day(s) ago')
  }
  else if(change > hour) {
    console.log('*', row[0], 'last checked out', Math.floor(change/hour), 'hour(s) ago')
  }
  else if(change > minute) {
    console.log('*', row[0], 'last checked out', Math.floor(change/minute), 'minute(s) ago');
  }
  else {
    console.log('*', row[0], 'last checked out', Math.floor(change/second), 'second(s) ago');
  }
});

git-post-checkout-hook-to-log-last-branch

#!/usr/bin/env node

var exec = require('child_process').exec;
var fs = require('fs');
var path = require('path');

var jsonPath = path.join(__dirname, '..', 'past-branches.json');
var now = Date.now();

exec('git branch --contains '+process.argv[2], function(err, stdout, stderr) {
  if(err) {
    console.error(stderr);
  }
  else {
    var branches = stdout.replace(/\* /, '').replace(/ /g, '').split('\n').filter(function(b) {
      return b !== '';
    });

    if(branches.length === 1) {
      var branch = branches[0];
      var past;
      try{ past = require(jsonPath); } catch(err) { past = []}
      past = past.filter(function(old) {
        return old[0] !== branch;
      });
      past.push([branch, now]);
      fs.writeFile(jsonPath, JSON.stringify(past, null, 2)+'\n', function(err) {
        if(err) {
          console.error('post-checkout can\'t write to past-branches');
        }
      });
    }

  }
});