npm-release.js

var fs = require('fs');
var child_process = require('child_process'); 

var PACKAGE_JSON_FILE = 'package.json';
var JSON_INDENT = 4;

function buildTagCmd(tagName) {
    return 'git tag ' + tagName
}

function buildCommitCmd(message) {
    return 'git commit -m "' + message + '" package.json; git push origin master'
}

function commitPackageFile(callback) {
    var cmd = buildCommitCmd('Incrementing version number for next iteration')
    exec(cmd, callback)
}

function tagRepo(tagName, callback) {
    var tagCmd = buildTagCmd(tagName)
    exec(tagCmd, callback)
}

function exec(cmd, callback) {
    console.log("Running %s", cmd)
    child_process.exec(cmd, callback)    
}

function readJSON(file) {
    var jsonStr = fs.readFileSync(PACKAGE_JSON_FILE)
    return JSON.parse(jsonStr);
}

function writeJSON(file) {
    var jsonStr = JSON.stringify(file, null, JSON_INDENT)
    fs.writeFileSync(PACKAGE_JSON_FILE, jsonStr)
}

function incrementVersionInJson(packageJson) {
    var version = packageJson.version.split('.');
    version[version.length-1]++;
    var newVersion = version.join('.');
    packageJson.version = newVersion;
    return newVersion;    
}

function tagAndIncrementVersion(callback) {
    var packageJson = readJSON(PACKAGE_JSON_FILE);
    var tagName = packageJson.name + '-' + packageJson.version
    tagRepo(tagName, function (error, stdout, stderr) {
        var newVersion = incrementVersionInJson(packageJson)
        console.log("Updating version in package.json to %s", newVersion)
        writeJSON(packageJson)
        commitPackageFile(function (error, stdout, stderr) {
            callback(packageJson.name, tagName)
        })    
    })
}

function checkoutAndPack(packageName, newTag) {
    var cmd = "rm -rf target; mkdir target; cd target; git clone ../.git code >/dev/null; cd code; git checkout " + newTag + " >/dev/null; npm publish;"
    exec(cmd, function (error, stdout, stderr) {
        var fileName = stdout.replace('./','').replace("\n", '')
         pushTag(newTag)
    })
}

function pushTag(tagName) {
    var cmd = 'git push origin ' + tagName
    child_process.exec(cmd, function (error, stdout, stderr) {
    })
}

tagAndIncrementVersion(function(packageName, newTag) {
    checkoutAndPack(packageName, newTag);   
})