When you write code with Tonic, the last statement in a code cell gets shown to you as an interactive result. This lets you quickly explore and test new ideas and is one of the most exciting features of Tonic. Of course, many things in node.js happen asynchronously, which can make things a bit more complicated.
Consider this code:
var request = require("request")
request.get("https://www.google.com", function(err, result)
The result won't be useful, because the request happens asynchronously. Fortunately, when you console.log with Tonic you'll still get a nice interactive object viewer. But with await we can do even better:
var request = require("request-promise")
This produces a much better output, because we don't get an unwanted undefined followed by the actual thing we wanted. And it more clearly expresses the desired behavior, in less code to boot.
How does it work? In short, you can await any value this is a Promise, and the execution will "pause" until the promise is fulfilled. You'll notice we used the promisified version of the request library above to make things easier for us. You'll find lots of promise ready libraries on npm, and more about async in this notebook.
The benefits become even more clear when you are working with a document that has more than one cell. If you simple use console.log, all of your results will show up at the end of your document, since all of the cells are first executed, and then the asynchronous results start coming in. When you use await you get the behavior you actually want: an asynchronous event happens, and then the result gets displayed, then finally the next code cell is run.
More about await