How it works...

During a web developer's day, a lot of repetitive tasks are executed: minification or compression (deleting whitespaces in the file), bundlisation (forming one file out of several files, so that there is only one file that uses only one HTTP request to send a few files to a client), validation of the CSS and JavaScript, compilation and code checking for TypeScript, CoffeScript, or CSS preprocessor, and minimizing and optimizing pictures so that you have different versions of your pictures according to the different platforms that your applications run on.

All these tasks can be done by a task runner. All task runners work with Node.js, and are composed of plugins written in JavaScript (like everything that works on Node.js). Grunt is the older task runner on Node.js, with more than 4,000 plugins, and is one of the most famous.