Consider using arrow functions for callbacks JS-0241
Anti-pattern
Minor
5 months ago
—
5 months old
Unexpected function expression
22 console.log(`Server :: Data received from client: ${chunk.toString()}`);
23 });
24
25 socket.on("end", function () {26 console.log("Server :: Closing connection with the client");27 _server.close();28 });29 });
30
31 _server.on("close", () => {Unexpected function expression
18 _server.on("connection", function (socket) {
19 socket.write("Hello, server.");
20
21 socket.on("data", function (chunk) {22 console.log(`Server :: Data received from client: ${chunk.toString()}`);23 });24
25 socket.on("end", function () {
26 console.log("Server :: Closing connection with the client");Unexpected function expression
15
16 await testUtils.sleep(100);
17
18 _server.on("connection", function (socket) {19 socket.write("Hello, server.");2021 socket.on("data", function (chunk) {22 console.log(`Server :: Data received from client: ${chunk.toString()}`);23 });2425 socket.on("end", function () {26 console.log("Server :: Closing connection with the client");27 _server.close();28 });29 });30
31 _server.on("close", () => {
32 console.log("Server :: Closing server.");Unexpected function expression
298 /**
299 * Emitted when the other end of the socket signals the end of transmission.
300 */
301 client.on("end", function () {302 logDebugNetwork("Connection ended.");303 });304
305 });
306}Unexpected function expression
291 /**
292 * Emitted once the socket is fully closed.
293 */
294 client.on("close", function (hadError: boolean) {295 logDebugNetwork(`Connection closed. Had Errors: ${hadError.toString()}`);296 });297
298 /**
299 * Emitted when the other end of the socket signals the end of transmission.
Description
It is recommended to use arrow functions as callbacks.
Arrow functions can be an attractive alternative to function expressions for callbacks or function arguments.
For example, arrow functions are automatically bound to their surrounding scope/context. This provides an alternative to the pre-ES6 standard of explicitly binding function expressions to achieve similar behavior.
Additionally, arrow functions are:
less verbose, and easier to reason about.
bound lexically regardless of where or when they are invoked.
Bad Practice
func(function(a) { return a; }); // ERROR
// prefer: func(a => a)
func(function() { return this.a; }.bind(this)); // ERROR
// prefer: func(() => this.a)
Recommended
// arrow function callback
func(a => a); // OK
// generator as callback
func(function*() { yield; }); // OK
// function expression not used as callback or function argument
var funcVar = function func(a) { return a; }; // OK
// unbound function expression callback
func(function() { return this.a; }); // OK
// recursive named function callback
func(function recursiveFunc(n) { return n && n + recursiveFunc(n - 1); }); // OK