MIME type check useless for file upload? (in particular, using the Javascript File API)?
file, javascript, mime, php, upload
Solution
The contributer is correct. You can't rely merely on MIME type checking to truly validate a file. It's only useful for quick lookups. For instance, on the client side, you can check the MIME type of a file before it is sent to the server, just in case the user chose the wrong file type, saving time and bandwidth. Apologies for the liberal use of commas!
Problem
I've got a server script receiving an uploaded file from Javascript. Client-side, using a `File` object (from the W3C File API) and code similar to this line: ``` if (file.type.indexOf("text") == 0) { ... } ``` one can perform a check of the file type. Apparently, this uses a MIME type (which returns these strings). In my journeys here through SO, I ventured across this worthy contributor, who maintains that MIME types are useless. Are MIME types indeed basically useless in a file upload situation, and any type checking should therefore occur server-side?