Async/Await in Express

We're calling this method, records.getQuotes, and 0:00 saving the result to a variable called quotes. 0:03 records.getQuotes reaches into our data store, gets all of the quotes, and 0:06 returns them to us. 0:10 Once we have all those quotes, we send them back to the client as JSON. 0:11 At the moment, however, we're getting back an empty object. 0:15 And this is because the getQuotes function is asynchronous. 0:18 All the functions in the records.js module use asynchronous functions to 0:22 closely mimic the behavior of an actual database. 0:27 And accessing a database is an inherently asynchronous operation, 0:30 meaning we can't be exactly sure when we're going to receive the information. 0:34 And in the meantime, JavaScript just keeps on going without waiting for 0:38 the data to return. 0:42 If you're new to the topic of asynchronous JavaScript, aren't familiar with promises, 0:44 or are totally new to async and await syntax. 0:48 I strongly recommend checking out the resources linked in the teacher's 0:51 notes below. 0:54 The getQuote function returns a promise, which uses Node's readFile method to 0:55 retrieve the data from the data.json file, then resolves the promise with that data. 1:01 The problem here is that the res.json method ends up running before 1:07 the getQuotes function has a chance to return any data. 1:12 JavaScript gets to this line of code and says, well, I guess there's 1:16 nothing in this quotes variable, and moves onto the next line of code. 1:19 The promise never has a chance to resolve, 1:23 and as a result, we end up sending back an empty object to the client. 1:26 What we need is a way to tell JavaScript, hey, stop. 1:30 Just hold on and wait for 1:33 this information to come back before running the next line of code. 1:34 We can do that using async and await. 1:38 We can await any function that returns a promise, so we'll await records.getQuotes. 1:40 This tells JavaScript to expect this method to return something, so 1:47 it shouldn't just give up on it and move on. 1:51 It should wait and tell this method, 1:54 return something to execute the next line of code. 1:56 The await function must be used inside of an async function. 1:59 This basically lets JavaScript know, hey, inside this function, we're going to ask 2:05 you to await some information before you speed on down the line. 2:10 So let's save and test this out by going back to the browser. 2:13 Refresh, and now we're returning our list of quotes. 2:17 There is some error handling that we could still do here, but 2:21 we'll get to that in a later video. 2:24 We'll continue to use async and await to build out the rest of our project. 2:26 So rest assured that we'll see and 2:30 talk about this again if you're still feeling unsure about it. 2:32 In the next video, we'll refactor our other get route to use our data store and 2:35 async await. 2:39