Simple API endpoint in NodeJs - node.js

Question

I'm trying to write a very simple API endpoint for a Udacity project I'm working on. When I try postman against the below endpoint, I get a promise rejection warning. I first attempted this using the 3 commented lines within this endpoint, but since it ran asynchronously, the file would not be ready before the delete function would run resulting in a file not found.
Any suggestions?
app.get( "/filteredimage", async ( req, res ) => {
var re = req.query.image_url;
if (!re){
return res.status(400).send(`id is required`);
}
var myfun = function (data, callback) {
var filteredpath = filterImageFromURL(data);
callback([filteredpath]);
};
myfun(re,deleteLocalFiles);
// let filteredpath = filterImageFromURL(re);
// res.sendFile(filteredpath);
// deleteLocalFiles([filteredpath]);
} );
Here are the util functions:
export async function filterImageFromURL(inputURL: string): Promise<string>{
return new Promise( async resolve => {
const photo = await Jimp.read(inputURL);
const outpath = '/tmp/filtered.'+Math.floor(Math.random() * 2000)+'.jpg';
await photo
.resize(256, 256) // resize
.quality(60) // set JPEG quality
.greyscale() // set greyscale
.write(__dirname+outpath, (img)=>{
resolve(__dirname+outpath);
});
});
}
// deleteLocalFiles
// helper function to delete files on the local disk
// useful to cleanup after tasks
// INPUTS
// files: Array<string> an array of absolute paths to files
export async function deleteLocalFiles(files:Array<string>){
for( let file of files) {
fs.unlinkSync(file);
}
}

Answer 1

Not much for TypeScript but I see a few issues:
One, you don't have to put a Promise in an async function because an async function is a Promise. Two, you're not awaiting filterImageFromURL() properly. And three, you should use try/catch blocks so that you don't get Unhandled Promise Rejection errors.
Forgive my stripping out of your TS.
app.get( "/filteredimage", async ( req, res ) => {
var myfun = async function (data, callback) {
try {
var filteredpath = await filterImageFromURL(data);
callback([filteredpath]);
} catch(err) {
console.error(err);
}
};
try {
var re = req.query.image_url;
if (!re) {
return res.status(400).send(`id is required`);
}
await myfun(re, deleteLocalFiles);
// let filteredpath = filterImageFromURL(re);
// res.sendFile(filteredpath);
// deleteLocalFiles([filteredpath]);
} catch(err) {
console.error(err);
}
});
export async function filterImageFromURL(inputUR) {
try {
const photo = await Jimp.read(inputURL);
const outpath = '/tmp/filtered.'+Math.floor(Math.random() * 2000)+'.jpg';
const img = photo
.resize(256, 256) // resize
.quality(60) // set JPEG quality
.greyscale() // set greyscale
.write(__dirname+outpath);
return img
} catch(err) {
console.error(err);
}
}