The Node Package Manager (npm) and the package.json file in combination makes a great option for build automation. Using npm and package.json is simpler and has no extra dependencies such as Gulp and Grunt for example. It's easy to get started by moving your existing commands into the package.json and you can utilize the entire Node package library in your script.
Why should I even care about this when there's an abundance of great tools already? npm is baked into your process already. No build tools are needed and any command you run at the command prompt today can be moved into your package.json with one line of code. The Node package library, that you most likely are using anyway, is vast and contains just about anything you need for your automation. Keeping it in npm and package.json means that everyone can use it. No additional configuration is needed. Just npm install and then use the scripts. You now only have one place to keep updated.