One of the best things about NodeJS callbacks is their consistency. As in, most API calls require one and their method signature always follows the same pattern, and this is the most beautiful bit.
The first parameter of a callback is always an error object (which is null if no error occurred). This seems a little counterintuative at first. When you stop and think about it though, it really isn’t at all. My initial though was that most of the time, it isn’t going to be used, so why isn’t the result of the computation the first parameter? Well, that might be nice, but chances are you’re actually going to have to check to see if an error occurred first, before you start using your results, since if a error did occur, you probably don’t have any results anyway! Secondly, Node is cleverly reminding you that you should check for and deal with errors as they happen by ensuring you define a first parameter in order to define a second parameter to get at the stuff you want.
If the error was the second (or last) parameter the chances are you’d forget to define it, or the lazy would simply neglect to define it. This could happen because in JavaScript all parameters to functions are optional. Just because you do or don’t define parameters to a function, doesn’t mean you can’t call it with or without parameters. The function might not work in either of these cases, but nevertheless it is still possible to call it. It seems that by not coercing the programmer into defining an error parameter and dealing with it their code could become less robust.
The error parameter in the callback function is a necessity of asynchronous programming because errors cannot usually caught with a try/catch block as the execution of the callback function usually doesn’t happen in the block of code surrounded by the try/catch but instead in a later run of the event loop. I much prefer this way of dealing with errors as opposed to searching through my library code to find out if I even need to surround a function call in a try/catch by figuring out if it even does an operation that could possibly throw an error…and you know what, it’s future proof, because even if a function does no operations that could cause an error, it doesn’t mean that in a future version it won’t. By defining an error parameter from the start you can deal with a future mishap, now that is awesome.
Thanks for the practical tips. More at german food
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали ремонт iphone 14 pro цены можете посмотреть на сайте: ремонт iphone 14 pro адреса Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
Nicely detailed. Discover more at colchones en Albacete
I found this very interesting. Check out staycation near mumbai for more
лучшие онлайн покер румы
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали ремонт iphone 14 pro цены можете посмотреть на сайте: ремонт iphone 14 pro сервис Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
Is there any specific preparation needed before visiting a chiropractor in Bonney Lake? # Chiropractic Care for Athletes Bonney Lake
Helpful suggestions! For more, visit neha physioedge spine pain treatment
Knowledgeable practitioners always aim provide utmost quality care possible…giving peace mind knowing everything h dental implants Mississauga
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали срочный ремонт iphone 14 pro можете посмотреть на сайте: ремонт iphone 14 pro Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
Looking for quality Sarasota painters? You can’t go wrong with the services offered by Sarasota residential painters
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали ремонт iphone 14 pro в москве можете посмотреть на сайте: ремонт iphone 14 pro рядом Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
Thanks for the great tips. Discover more at roof replacement near me
онлайн покер на деньги в россии
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали ремонт iphone 14 pro рядом можете посмотреть на сайте: срочный ремонт iphone 14 pro Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
This was highly helpful. For more, visit Affordible Pest Solutions
Bail bonds are more common than you think! Educate yourself by visiting the informative site, https://jorgusspfi.livejournal.com/profile/
The challenges of navigating healthcare services can be overwhelming; I found excellent guidance at elderly home care plans
покер на реальные деньги
Burlington сантехника купить можно в фирменных магазинах
и у официальных дилеров. Продукция этой марки отличается элегантным дизайном и высоким качеством.
You really nailed the common plumbing issues! For more expert advice, visit this link: my plumber
I’m with you—insects are absolutely disgusting! It appears like they’re anywhere these days. For techniques to cast off them, talk over with this valuable website: pest control company
Can anyone recommend a good strain from Firehouse365? I’m looking to try something new! weed store
покер казино онлайн
I recently switched to a holistic dentist holistic dentist los angeles
I appreciated this article. For more, visit pest control all india pest control andheri
KANNA Weed Dispensary is my go-to spot in Oakland! Love their selection. Check out more at Weed near me
Nicely detailed. Discover more at hair cutting
Thanks for the insightful write-up. More like this at dr thakur pediatric dentist borvali
Such valuable information about maintaining an old roof versus investing in a new one; it’s great food for thought—find out more at roofing contractors
Предлагаем услуги профессиональных инженеров офицальной мастерской. Еслли вы искали ремонт iphone 14 pro адреса можете посмотреть на сайте: ремонт iphone 14 pro Наши мастера оперативно устранят неисправности вашего устройства в сервисе или с выездом на дом
Se stai cercando un sito web utile per scoprire le migliori attività a Bologna, ti consiglio di visitare web agency bologna
покер на деньги с выводом средств на карту
Saya sangat terkesan dengan detail dan presisi dari hasil kerja bengkel bubut kota medan
Exploring new dimensions of consciousness through fashion is so exciting! Discover your style at aztec style apparel
When planning a wedding, make sure you include quality restroom rentals like those from portable toilet rental service victorville ca
I’m considering chiropractic adjustments for my back pain—should I choose a Bonney Lake chiropractor? Chiropractor Bonney Lake WA
The reside track situations at wineries can pretty develop the trip! Had a blast at best winery experiences with good sized tunes and even more advantageous wine
Internet marketing is essential for enterprises in Kelowna to achieve their audience and Raise on the net visibility. Have a look at SEO Kelowna WILDFIRE SEO AND INTERNET MARKETING for expert approaches and solutions
Is it common to have both relaxation and medical treatments at a medical spa? I’m interested in exploring this option emsculpt neo
Thanks for the insightful write-up. More like this at san diego storage and movers
My friend told me about iphone repair , and now I’m a loyal customer after my first visit
This was very insightful. Check out san diego storage and moving for more
Very useful post. For similar content, visit best moving companies san diego
онлайн покер с бездепозитным бонусом за регистрацию
Valuable information! Find more at san diego moving companies
This was a wonderful post. Check out moving and packing san diego for more
This was a wonderful guide. Check out san diego local moving companies for more
Thanks for the clear advice. More at moving companies near me
This was beautifully organized. Discover more at office moving companies near me