CORS, Preflight Request, OPTIONS Method | Access Control Allow Origin Error Explained

- What is CORS?
- What is Cross Origin?
- Are subdomain, host, port, protocol fall under Cross-Origin mechanism?
- How does Cross Origin Request Sharing works behind the scenes?
- What is CORS preflight?
- What is the OPTIONS call?
- What are the additional HTTP Headers required?
- Does server always make Preflight options call in CORS protocol?
- What browser versions support CORS?
- Access Control Allow Origin Error?
- How to solve CORS Error?
- How to resolve CORS issue in Google Chrome?

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Akshay Saini

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[vikramkrish]

Hi Akshay, I learned a lot from this video. However I have a small correction to point out. At 06:50 you have written it as `accept-control-allow-origin: * ` while it is `access-control-allow-origin: *`. Extremely sorry for pointing out but some other beginner may capture it wrongly. Kindly put a patch message on screen while that portion is playing.

[primetech]

"Thank you, my friend, for providing such a straightforward and simplified explanation of how CORS works. Your explanation has helped me understand this topic better. Great job!"

[haverikakrishna]

This is the reason why every developer is the fan and in love with you, you teach the things in the way they are to be delivered to the consumers/audience..
I want to mention this to, before whenever I used to watch content of any other youtuber it was quite obvious that I yawned for 2-3 times, but here whenever I watch your videos I never do that (or it wont come also), instead at this time I was very sleepy, but before going to sleep I just want to clear out this topic and now here I'm ready to move to you another video with full energy.
Thanks bhaiya for making such a wonderful content..😍😍

[abhishekvishwakarma]

Recently (two days back😁) I had my Full-stack Interview and they asked me about the middlewares😅 (Which I explained Using the example of Cors :) but that time I have only a little knowledge about cors (The interview went well but this question really scratch my head) And now after this, I can explain cors easily thanks to you sir😁🔥

[garudkardnyaneshwar]

Bhai tune jo bataya na jis way m, jaise explain kiya man gaya teko aajtk smjhi nahi thi ye concept etni achese thank you man

[rank]

Apart from detailed content, I admire your effort for including commonly asked interview questions.

[thatsalot]

ok this is the first time someone actually explained what CORS is instead of just giving 10 different ways to get rid of the error, just a header ! lol

[ayushbhardwaj]

No other video could explain CORS soo briefly and easily. Thankyou Akshay♥️♥️

[AbdulQadir-ebvi]

Amazing work. I like the idea of explaining to whiteboard, really helped me understand the logic behind cors, this is what great teachers do.

[thesudeshdas]

Finally, I understand how CORS works. This was awesome. Got to learn a lot.

[rohitkudalkar]

Thank you so much sir. I was searching for the same in few months back, Today randomaly i watched your video and get to know that why my react app was not able to fetch data from API when i run it on another server like 3001. Thanks you so much sir for sharing your Efforts and knowledge. Love ❤️ and Support.

[abhishekpradhan]

Somehow he managed to clear the interview, that doesn't mean anyone can clear the interview by following these videos

[HarshSingh-hkfe]

the way you explain cors is outstanding really loved it <3

[animeshsharma]

Hi Akshay, thanks for your extremely helpful videos. Would request you to please help to understand the concept of microservices and how a JavaScript based app fits into this

[nabhoyar]

Thanks Akshay for sharing beautiful explanation about CORS. Its really most frequently asked questions in interview.

[sohamkamanitech]

These are a great set of videos! Keep up the good work :)

[meenakshigupta]

Please make a video on web workers and service workers. I find it hard to understand. Your videos are very informative..Thanks a lot for sharing them.

[vasilvasilev]

Very explicit and right to the point explanation!

[shikhakumari]

Hey Akshay, thanks a lot for uploading such informative videos. Could you please upload tutorials on JS Engine and how Web APIs, Callback Queues, Event loop works together with JS Engine to run JS on browser

[sameergaikwad]

Thanks Akshay :) This really helped in my understanding of CORS concept and resolving most request calls issue while developing projects :)