In Express.js, you can add type to an error handler middleware function by importing the ErrorRequestHandler type from express package like so:
import type { ErrorRequestHandler } from 'express';
You may add the type to the error handler function in the following ways:
// ...
const errorHandler: ErrorRequestHandler = (err, req, res, next) => {};
app.use(errorHandler);
// ...
app.use(((err, req, res, next) => {}) as ErrorRequestHandler);
If you haven't installed the type definitions for Express.js, then make sure to add them to the dev dependencies list in your package.json, for example, like so:
npm install --save-dev @types/express
Hope you found this post useful. It was published . Please show your love and support by sharing this post.