How to avoid redundant code writing promises? - node.js

Question

I have a file where multiple export functions that are invoked from api's and each of these methods will make some get/post inside the function.
so my questions is for Promise.all that looks redundant to me is there better approach to achieve this using one private method handler that can be implemented or invoked from each of those export function and return response.
main.ts
export function getUser(req: Request, res: Response) {
const p1 = Promise.resolve("data1");
const p2 = Promise.resolve("data2");
Promise.all([p1,p2])
.then(function(results) {
res.json(results);
})
.catch(function(e) {
console.log(e)
});
}
export function getRanks(req: Request, res: Response) {
const p1 = Promise.resolve("data3");
const p2 = Promise.resolve("data4");
Promise.all([p1,p2])
.then(function(results) {
res.json(results);
})
.catch(function(e) {
console.log(e)
});
}

Answer 1

You can do exactly what you wrote - create function that does the general handling.
export function getUser(req: Request, res: Response) {
const p1 = Promise.resolve("data1");
const p2 = Promise.resolve("data2");
sendResponse(req, res, [p1,p2]);
}
export function getRanks(req: Request, res: Response) {
const p1 = Promise.resolve("data3");
const p2 = Promise.resolve("data4");
sendResponse(req, res, [p1,p2]);
}
function sendResponse(req, res, promises) {
Promise.all(promises)
.then(function(results) {
res.json(results);
})
.catch(function(e) {
console.log(e)
});
}
PS: You should have some res handling in .catch (res.end() or res.status(500); res.json({error: e})) otherwise the request will be hanging on for 30-90sec (based on your settings)

Answer 2

In case p1, etc. promises are really created Promise.resolve, it could be omitted; Promise.all accepts regular values.
It could be written with async..await in more succinct manner:
export async function getUser(req: Request, res: Response) {
...
try {
const results = await Promise.all([p1, p2]);
res.json(results);
} catch (e) {
console.log(e)
}
}
At this point functions don't need to be DRYed any further.