Disallow empty functions
Empty functions can reduce readability because readers need to guess whether it’s intentional or not. So writing a clear comment for empty functions is a good practice.
Especially, the empty block of arrow functions might be confusing developers. It’s very similar to an empty object literal.
list.map(() => {}); // This is a block, would return undefined.
list.map(() => ({})); // This is an empty object.
This rule is aimed at eliminating empty functions. A function will not be considered a problem if it contains a comment.
Examples of incorrect code for this rule:
/*eslint no-empty-function: "error"*/
/*eslint-env es6*/
function foo() {}
var foo = function() {};
var foo = () => {};
function* foo() {}
var foo = function*() {};
var obj = {
foo: function() {},
foo: function*() {},
foo() {},
*foo() {},
get foo() {},
set foo(value) {}
};
class A {
constructor() {}
foo() {}
*foo() {}
get foo() {}
set foo(value) {}
static foo() {}
static *foo() {}
static get foo() {}
static set foo(value) {}
}
Examples of correct code for this rule:
/*eslint no-empty-function: "error"*/
/*eslint-env es6*/
function foo() {
// do nothing.
}
var foo = function() {
// any clear comments.
};
var foo = () => {
bar();
};
function* foo() {
// do nothing.
}
var foo = function*() {
// do nothing.
};
var obj = {
foo: function() {
// do nothing.
},
foo: function*() {
// do nothing.
},
foo() {
// do nothing.
},
*foo() {
// do nothing.
},
get foo() {
// do nothing.
},
set foo(value) {
// do nothing.
}
};
class A {
constructor() {
// do nothing.
}
foo() {
// do nothing.
}
*foo() {
// do nothing.
}
get foo() {
// do nothing.
}
set foo(value) {
// do nothing.
}
static foo() {
// do nothing.
}
static *foo() {
// do nothing.
}
static get foo() {
// do nothing.
}
static set foo(value) {
// do nothing.
}
}
This rule has an option to allow specific kinds of functions to be empty.
allow
(string[]
) - A list of kind to allow empty functions. List items are some of the following strings. An empty array ([]
) by default. "functions"
- Normal functions."arrowFunctions"
- Arrow functions."generatorFunctions"
- Generator functions."methods"
- Class methods and method shorthands of object literals."generatorMethods"
- Class methods and method shorthands of object literals with generator."getters"
- Getters."setters"
- Setters."constructors"
- Class constructors."asyncFunctions"
- Async functions."asyncMethods"
- Async class methods and method shorthands of object literals.Examples of correct code for the { "allow": ["functions"] }
option:
Examples of correct code for the { "allow": ["arrowFunctions"] }
option:
Examples of correct code for the { "allow": ["generatorFunctions"] }
option:
Examples of correct code for the { "allow": ["methods"] }
option:
Examples of correct code for the { "allow": ["generatorMethods"] }
option:
Examples of correct code for the { "allow": ["getters"] }
option:
Examples of correct code for the { "allow": ["setters"] }
option:
Examples of correct code for the { "allow": ["constructors"] }
option:
Examples of correct code for the { "allow": ["asyncFunctions"] }
options:
Examples of correct code for the { "allow": ["asyncMethods"] }
options:
If you don’t want to be notified about empty functions, then it’s safe to disable this rule.
This rule was introduced in ESLint v2.0.0.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/no-empty-function