Mastering TypeScript 3 - Third Edition

Using promises

Promises provide a simple syntax for handling these resolve and reject functions. Let's take a look at how we would use the promises defined in our previous code snippet, as follows:

function callDelayedPromise() { 
    console.log(`calling delayedPromise`); 
    delayedPromise().then( 
        () => { console.log(`delayedPromise.then()`) } 
    ); 
} 
 
callDelayedPromise(); 

Here, we have defined a function named callDelayedPromise. This function logs a message to the console, and then calls our delayedPromise function. We are using fluent syntax to attach to the then function of the promise, and defining an anonymous function that will be called when the promise is resolved. The output of this code is as follows:

calling delayedPromise
delayedPromise.then() ...