Get file extention using only file name in javascript

I am creating a discord bot (irrelevent) that sends images into the chat. The user can type out the name of the image without needing to type the file extention. The problem is that the bot doesn’t know what the file extention is so it will crash if the picture is a .jpg and the program was expecting a .png. Is there a way to make the program not require a file extention to open the file?

let image = imageName;{ files: [`media/stickers/${imageName}.png`] });


Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Using fs – specifically the Promise version of fs, makes this quite simple

import { readdir } from 'fs/promises';

const getFullname = async (path, target)  => 
    (await readdir(path))
    .find(file => 
        file === target || file.split('.').slice(0,-1).join('.') === target
try {
    const actualName = await getExtension('media/stickers', imageName);
    if (!actualName) {
        throw `File ${imageName} not found`;
    }{ files: [`media/stickers/${actualName}`] });
} catch(error) {
    // handle your errors here

You can pass in the name with or without the extension and it will be found – note, this is NOT case insensitive … so XYZ won’t match xyz.jpg – easily changed if you need case insensitivity

Method 2

Unfortunately, the extension of the filename is required. You know file.mp4 and file.mp3 is entirely different.

However, you can use a try-except and a for loop to get the correct file!

I would suggest:

let image = imageName;
let extensions = [".png", ".jpg", "gif"] // All the extensions you can think of 
const pass = () => {}
for (const extension of extensions) {
  try {{ files: [`media/stickers/${imageName}${extension}`] }); // successfully get file and send
  } catch(error) {
     pass() // do nothing, and go back to the loop and test other extension

I haven’t tried that before, and I am a Python programmer. But I hope you get the idea.

Method 3

There are only a few known image extensions like jpg, png, gif, jpeg. Maybe try and fetch the file with best guess extension, if it throws exception try the next format.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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