Dependency Injection in JavaScript

[@leetcodeking4859]

Thank you Sam. Please keep making videos. You are 1000% easier to understand than my teachers. You are a life send. Thank you 100 times.

[@AmberCheaaa]

This was very clear. I was struggling to understand the concept but with this I get it completely now! Thanks

[@NeilTruick]

My primary development language is C#, so I was very interested in learning how to mock for testing in TypeScript. I've got a few years of JavaScript under my belt, but never got into DI there. I came to this video from your "Mocking a Database in Jest" video. If the explanation is clear there as it was here, you have my deepest gratitude and appreciation, as well as a new subscriber.

[@vesh95]

Thanks. Спасибо! Почему-то я не догадывался строить приложение таким образом. Возможно под влиянием laravel и других фреймворков я упускал понимание работы механизмов более низкого уровня и пытался реализовать создание корневого объекта приложения во входном файле. Очень рад, что посмотрел данное видео)

[@sheikhahnafhasan2830]

You got a sub bro. You're awesome. Your channel will get 1M hit too soon. I hope. You've very quality content. Please, make a playlist on React testing too

[@rickvian]

great explanation just a small feedback that your music is louder than your voice and thats kind of annoying

[@gb469x]

Code Fastforwards : 3:25 - database.js 6:55 - wrapping database calls in app.js inside a function 9:00 - passing a custom database object to the app

[@eduardocarvalho4232]

Very nice explanation. Thanks Sam. Greetings from Portugal 🤗

[@alvaro1121]

Thank you and kudos! Very easy to understand, and you give a lot of great examples that can fit right into real life projects.

[@leovvvvv]

Thanks for the great tutorial, Sam! One feedback though; the music is a bit louder than your voice, so I have to decrease the volume whenever you fast forward

[@learningforever2531]

Hi, In case we separate the route and controller (move the route to route file, controller to controller file), how we inject database

[@ilhamkaddouri7038]

This is great looking forward advanced topics about testing! Thank you

[@sajjad.ilcsms]

Great example, finally i get it

[@maxlupey2787]

Awsome explanation

[@aliasanov8790]

Great explanation! Keep it going please :-)

[@marioserano4098]

it was a very clear explanation, very cool!

[@Tozaroo]

this was awesome, thank you!

[@alfonsoramirezelorriaga1153]

Great way to explain the pattern. Thank you! Just one question, is having all your queries to the db in a single file a good practice or a conventional practice? I just have not seen that before.

[@martinvanlaethem543]

good stuff

[@clasesutnfrc8699]

05:32 Use Dependency Injection

[@saulramirez727]

Great video

[@nimser]

Super nice, thanks. How would you do if the database isn't directly used in the app, but in a router or in a controller called from that router ? I'm having a hard time trying to apply these principles to an app wired this way.

[@sammygopeh7578]

Another amazing....THANK YOOOUU SAM!!

[@SamMeechWard]

Glad you enjoyed it!

[@jimmyfitzsimmons7170]

Love your work dude but the songs u play during your fastforward makes me want to throw away my headphones everytime ^^

[@SamMeechWard]

🤣 I’m open to music suggestions

[@lexNwimue]

Great explanation. Succint! Just need to reduce the volume of the music though. It'll be better if it played somewhat subtly in the background. 👍

[@joshj.7764]

Thanks for making this video! I've always liked test-driven development. But I do have a question - what's the syntax for injecting the database dependency if your routes are in another file? for example app.ts has: app.user('/api/user', userRoute); //where your post route is in userRoute.js

[@Sam-nm1ix]

Did you hire a professional to select your intro songs? They're always so good.

[@SamMeechWard]

I have an unpaid intern

[@Sam-nm1ix]

@@SamMeechWard you should start paying her

[@AndreaCiani]

Great tutorial!!! Thanks!!

[@tukuyoma]

please how do I achieve dependency injection when I have different route files and import all the routes into the index app

[@SamMeechWard]

I hope this makes sense, i'm just going to write the code in the youtube comment // someRoute.js const express = require('express') export function(database) { const route = express.route("/something") route.get("/", (req, res) => {}) return route } // app.js const makeSomeRoute = require('./someRoute.js') .... makeSomeRoute(database)

[@herrklaus]

@@SamMeechWard wouldn't this be express.Router?

[@thatsalot3577]

But what if you have a lot of routes and they're stored in different files, do I have to drill down the database object to every single controller and middleware ?

[@gosnooky]

Technically, ,if a username already exists you would use the 409 Conflict status. I know it's not germane to the tutorial, it's just a random nugget of information for anyone who builds HTTP servers. I always suggest using HTTP status semantics so consuming applications can derive the error from the calling context without having to parse the error message text, or introducing custom domain-specific error codes. Then for a specific request, the front-end say, will know that when a conflict is thrown, a user with the username already exists.

[@snake1625b]

what if youre using controllers for each route, then you wouldnt be creaitng the app in each controller right?

[@mertgenc9890]

hey thanks a lot for the amazing video. could you make a video about applying dependency injection to graphql server?

[@SamMeechWard]

I love the suggestions. It might be a while until I do any videos with GraphQL though.

[@indestructible-today]

You talk, and I hear henry cavill's voice. great tutorial btw.

[@armanabrahamyan9714]

it is wonderful

[@berkaybayrak7876]

I have a question, what if my requestHandlers are different file how can ı send database

[@alexpiano]

NIce videos. If I may, each time you put a music I find the volume is a little too high and kinda distuptive for focusing. Anyway, I just silenced these parts. Keep up the good work.

[@EvgenyT2011]

Thanks!

[@Richie43]

You need to use Typescript and tsyringe

[@valentoMundrov]

Greetings, thank you for the nice video (all of them), here is my question: If createApp imports a function, doesn't it executes it straight by importing it? Don't you instantiate two apps now? Isn't it better to assign your app-function into an Object and export the object, instead, so you can initiate the app from your server code?... or I'm just wrong :) ps. I understand the video is just basic, yet the question is for my own sake :)

[@ehSamurai3483]

Isn't this the Strategy Pattern?

[@davidkhierl696]

music too loud

[@AllanAlmeidaOficial]

Good vídeo, but please don’t put that song so loud, it’s really annoying

[@babykosh5415]

This (TDD) is a niche market ... no one is paying attention too....keep at it

[@bariswheel]

Great stuff but music not my cup of tea at all, please turn it down a bit, too distracting