Build Reactive Websites with RxJS

Calling next with Schedulers

You’ve learned a heaping pile of different ways to create observables throughout this book. The secret you didn’t know was how Rx decides exactly when to send a new value down the chain. The tool Rx uses for this is called a scheduler, and Rx ships many options for you to choose from. By default, every observable does not use a scheduler to plan out events, instead they emit all values synchronously. Run the following code to see this in action:

of('Hello')
.subscribe(next => console.log(next));

console.log('World');

This snippet does not pass a scheduler into the of constructor, so it just runs synchronously. This example logs Hello before World. Now, we can add the asap scheduler to the mix, which delays ...