`git log` in javascript

git-log.js

fs = require('fs');

//  get and parse the HEAD
var HEAD = fs.readFileSync("./.git/HEAD").toString();
HEAD = HEAD.replace(/(\r\n|\n|\r)/gm,"");
HEAD = HEAD.split(": ")[1]
var HEADpath = fs.readFileSync('./.git/' + HEAD).toString().replace(/\n/, "");

//  function to print pretty output
var exec = require('child_process').execSync;

printPretty = function(hash){
        // make author pretty
        pretty = exec("git cat-file -p " + hash).toString();
        pretty = pretty.replace(/parent .*\n/,"");
        pretty = pretty.replace(/tree .*\n/,"");
        pretty = pretty.replace(/committer .*\n/,"");
        pretty = pretty.replace(/author/, "Author:")

        // make time pretty
        time = pretty.split('\n')[0].replace(/Author: .*\> /, "");
        time = new Date(time.split(' ')[0] * 1000)
        date = time.toDateString();
        time = time.toTimeString();
        pretty = pretty.replace(/\> .*\n/g,"\>\n");

        //make message pretty
        message = pretty.split('\n').slice(-2, -1)[0];
        pretty = pretty.replace(message, "    " + message);

        // color commit line
        console.log('\x1b[33m%s\x1b[0m', "commit " + hash);
        console.log("Date: " + date + " " + time);
        console.log(pretty);
}

// recursive function to traverse tree
//  follows `parent` until `parent`
//  is no longer found
getParent = function(hash){
        re = new RegExp('parent');
        var commit = exec("git cat-file -p " + hash).toString();
        parent = commit.split("\n")[1];
        if(re.test(parent)){
                parent = parent.split(" ")[1];
                printPretty(hash);
                getParent(parent);
        }
        else{
                printPretty(hash);
        }
}

// run
getParent(HEADpath);