Windows unexpected mime type

[bryns1]

The problem:

I have a single roster.csv file synced between my PC and Mac. When uploading the file from windows, it doesn't return it's mime type in the file object, instead you get type:"". (Unless you have excel installed then it returns an excel specific type)

Examples of file types returned: Linux/Mac returns type:"text/csv" Windows returns type:"" (empty) Windows with Excel returns type:"application/vnd.ms-excel" (Assuming the mime type would change with other programs as well)

This makes it nearly impossible to let my app reliably accept .csv files across platform.

So I was wondering for a solution, would it be possible to use something similar to this?

let type = currentFiles[i].type;
if(!type){
    let textType = currentFiles[i].name.substring(currentFiles[i].name.lastIndexOf("."), 
    currentFiles[i].name.length); // based off https://stackoverflow.com/a/1203361/4105381, includes "." in file name
    type =  textType.length != currentFiles[i].name.length ? textType : undefined; // Returning undefined for readability, maybe return ""
}
// let fileTypeIndex: number = this.supportedFileTypes.indexOf(type);

https://codepen.io/bryn/pen/mwPrmB/

Obviously we can't set "" but [".csv", "text/csv"] would work

Another cool solution would be to allow developers to write their own validation functions that they can parse to File Drop.

function myCustomValidator(file){
   let myValidList = [".csv"];
   let textType = file.name.substring(file.name.lastIndexOf("."), file.name.length);
   let isValid = myValidList.indexOf(textType) !== -1;
   if(isValid){
      return {valid: true};
   }else{
       return {valid: false, reason:"reason"};
   }
}

I'm still relatively new to the coding scene. Tell me if any of this sounds doable/reasonable