ES7's "await" feature
Consider this code:
The result won't be useful, because the request happens asynchronously. Fortunately, when you
var request = require("request")
request.get("https://www.google.com", function(err, result)
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") await request.get("https://www.google.com")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.