What are route handlers?

Q: What are route handlers?

app.get('/example/a', (req, res) => { res.send('Hello from A!') }) //More than one callback function can handle a route (make sure you specify the next object). For example: app.get('/example/b', (req, res, next) => { console.log('the response will be sent by the next function ...') next() }, (req, res) => { res.send('Hello from B!') }) //An array of callback functions can handle a route. For example: const cb0 = function (req, res, next) { console.log('CB0') next() } const cb1 = function (req, res, next) { console.log('CB1') next() } const cb2 = function (req, res) { res.send('Hello from C!') } app.get('/example/c', [cb0, cb1, cb2]) //A combination of independent functions and arrays of functions can handle a route. For example: const cb0 = function (req, res, next) { console.log('CB0') next() } const cb1 = function (req, res, next) { console.log('CB1') next() } app.get('/example/d', [cb0, cb1], (req, res, next) => { console.log('the response will be sent by the next function ...') next() }, (req, res) => { res.send('Hello from D!') })

Difficulty: 5/10

routing, middleware, error handling

A route handler is a function that gets executed when an HTTP request hits a specific route (URL path) on your server. You can provide multiple callback functions that behave like middleware to handle a request. The only exception is that these callbacks might invoke next('route') to bypass the remaining route callbacks. You can use this mechanism to impose pre-conditions on a route, then pass control to subsequent routes if there’s no reason to proceed with the current route.

Route handlers can be in the form of a function, an array of functions, or combinations of both, as shown in the following examples. A single callback function can handle a route.

Scenario Questions

0-2 years experience

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