Escape Callback Hell and Enter Callback Heaven with Async/Await Jennifer Bland

Who Am I? www.jenniferbland.com @ratracegrad www.youtube.com/c/JenniferBland jennifer@jenniferbland.com github.com/jenniferbland

IN THE BEGINNING or how did we get here

The only thing that maters in software is the experience of the user Change How I/O Is Handled

Sample Code

CHANGE THE INFRASTRUCTURE non-blocking event loop

Node.js Design Goals No function should direct perform I/O To receive info from disk, network or other process, there must be a callback Stream everything; never force the buffering of data Have built-in support for important protocols

Progression of I/O Handling

Sample Code - no waiting

Sample Code - callback

Sample Code - callback hell

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Promises

Chaining Promises

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Async Await Async - declares an asynchronous function Automatically transforms a regular function into a Promise When called async functions resolve with whatever is returned in their body Async functions enable the use of await

Async Await Await - pauses the execution of async functions When placed in front of a Promise call, await forces the rest of the code to wait until that Promise finishes and returns a result Await works only with Promises, it does not work with callbacks Await can only be used inside async functions

Async/Await Example

Async/Await Detailed Example

Async/Await Handling Errors

Async/Await Handling Errors

Async/Await Handling Errors

Async/Await Examples

Async/Await Examples

Async/Await Examples

Async/Await Examples

Browser Support

Who Am I? www.jenniferbland.com @ratracegrad www.youtube.com/c/JenniferBland jennifer@jenniferbland.com github.com/jenniferbland