Proper way to remove middleware from the Express stack?

Question

Is there a canonical way to remove middleware added with app.use from the stack? It seems that it should be possible to just modify the app.stack array directl

Answer 1

There seems to be no built in way to do that, but you can manage to get the same result with a small trick. Create your own array of middleware (let's call it dynamicMiddleware) but don't push that into express, instead push just 1 middleware that will execute all the handlers in dynamicMiddleware asynchronously and in order.

const async = require('async')

// Middleware 
const m1 = (req, res, next) => {
    // do something here 
    next();
}

const m2 = (req, res, next) => {
    // do something here 
    next();
}

const m3 = (req, res, next) => {
    // do something here 
    next();
}

let dynamicMiddleware = [m1, m2, m3]

app.use((req, res, next) => {
    // execute async handlers one by one
    async.eachSeries(
        // array to iterate over
        dynamicMiddleware, 
        // iteration function
        (handler, callback) => {
            // call handler with req, res, and callback as next
            handler(req, res, callback)
        }, 
        // final callback
        (err) => {
            if( err ) {
            // handle error as needed

            } else {
                // call next middleware
                next()
            }
        }
    );
})

The code is a bit rough as I don't have a chance to test it right now, but the idea should be clear: wrap all dynamic handlers array in 1 middleware, that will loop through the array. And as you add or remove handlers to the array, only the ones left in the array will be called.