Live preview of Vega visualizations.

Vega is a declarative language for making data visualizations. It's bona fide awesome. Check it out.

This is a tiny tool for quickly viewing Vega visualizations, complete with live updates. You can live-code your visualization in your favorite editor. Or you can automatically see updates as new points are added to a data file---so you can watch an experiment progress in real time.

Vegalive is written for Node.js, so it's installed with npm. Just type:

$ npm install -g vegalive

Then, go to a directory that has one of your Vega specs (i.e., .json files) and type:

$ vegalive

As the output suggests, you'll then want to point your browser at http://localhost:4915. There you'll see a list of JSON documents in the current directory. Click on your plot's filename to see it rendered in glorious HTML5.

Then the magic happens:

• Edit the spec in your favorite editor. Whenever you save, the plot refreshes in your browser.

• Edit the data files that your visualization uses (or have another tool update them). The plot refreshes automatically.

There's also a screencast.

Vegalive is by Adrian Sampson. It is made available under the BSD three-clause license, the same license as Vega itself. Vega is by Trifacta, which is unaffiliated.