ESLintSuggest using arrow functions as callbacks. (prefer-arrow-callback)
Arrow functions are suited to callbacks, because:
thiskeywords in arrow functions bind to the upper scope’s.- The notation of the arrow function is shorter than function expression’s.
Rule Details
This rule is aimed to flag usage of function expressions in an argument list.
The following patterns are considered problems:
/*eslint prefer-arrow-callback: 2*/
foo(function(a) { return a; }); /*error Unexpected function expression.*/
foo(function() { return this.a; }.bind(this)); /*error Unexpected function expression.*/
The following patterns are not considered problems:
/*eslint prefer-arrow-callback: 2*/
/*eslint-env es6*/
foo(a => a);
foo(function*() { yield; });
// this is not a callback.
var foo = function foo(a) { return a; };
// using `this` without `.bind(this)`.
foo(function() { return this.a; });
// recursively.
foo(function bar(n) { return n && n + bar(n - 1); });
When Not To Use It
This rule should not be used in ES3/5 environments.
In ES2015 (ES6) or later, if you don’t want to be notified about function expressions in an argument list, you can safely disable this rule.
Version
This rule was introduced in ESLint 1.2.0.