How to know if the file is correct?

Question

JavaScript

Hello, please answer, how do I know that the file is correct?
That is, the user created a file with the jpg extension, how to find out the authenticity of the file?
How to implement it? Thanks in advance)

Answer 1

Check by mime type, or there is an option with getimagesize
Yes, and if you google it, there are a lot of handy libraries for uploading files in PHP that have the functionality you need.