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Is there a reason not to use arrows instead of regular function expressions in expressjs for handlers in middleware?
app.use(mountSomething())
router.use(mountSomethingElse())
app.get('/', (req,res,next)=> {
next();
})
route.get('/path', (req,res,next)=>{
res.send('send')
})
559
It's a new feature that introduced in ES6 and is called arrow function. The left part denotes the input of a function and the right part the output of that function.
An arrow function doesn't have its own this value and the arguments object. Therefore, you should not use it as an event handler, a method of an object literal, a prototype method, or when you have a function that uses the arguments object.
Arrow function is one of the features introduced in the ES6 version of JavaScript. It allows you to create functions in a cleaner way compared to regular functions. For example, This function // function expression let x = function(x, y) { return x * y; }
an arrow function is an expr, but we need surrounding parens b/c of "operator precedence" (sorta), so that the final parens to invoke the arrow-IIFE apply to the entire function and not to just the last token of its body.
app.get('/', (req,res,next)=> {
next();
})
is the same as
app.get('/', function(req,res,next) {
next();
}.bind(this))
In most cases you are not going to use 'this'(which will be probably undefined) in the handlers, so you are free to use arrow functions.
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