eslint/func-names Style
What it does
Require or disallow named function expressions.
Why is this bad?
Leaving the name off a function will cause <anonymous> to appear in stack traces of errors thrown in it or any function called within it. This makes it more difficult to find where an error is thrown. Providing an explicit name also improves readability and consistency.
Options
First option:
- Type:
string - Default:
"always" - Possible values:
"always"- requires all function expressions to have a name."as-needed"- requires a name only if one is not automatically inferred."never"- disallows names for function expressions.
Second option:
- Type:
object - Properties:
generators:("always" | "as-needed" | "never")(default: falls back to first option)"always"- require named generator function expressions."as-needed"- require a name only when not inferred."never"- disallow names for generator function expressions.
Example configuration:
json
{
"func-names": ["error", "as-needed", { "generators": "never" }]
}Examples
Examples of incorrect code for this rule:
js
/* func-names: ["error", "always"] */
Foo.prototype.bar = function() {};
const cat = { meow: function() {} };
(function() {/* ... */})();
export default function() {}Examples of correct code for this rule:
js
/* func-names: ["error", "always"] */
Foo.prototype.bar = function bar() {};
const cat = { meow() {} };
(function bar() {/* ... */})();
export default function foo() {}as-needed
Examples of incorrect code for this rule with the "as-needed" option:
js
/* func-names: ["error", "as-needed"] */
Foo.prototype.bar = function() {};
(function() {/* ... */})();
export default function() {}Examples of correct code for this rule with the "as-needed" option:
js
/* func-names: ["error", "as-needed"] */
const bar = function() {};
const cat = { meow: function() {} };
class C {
#bar = function() {};
baz = function() {};
}
quux ??= function() {};
(function bar() {/* ... */})();
export default function foo() {}never
Examples of incorrect code for this rule with the "never" option:
js
/* func-names: ["error", "never"] */
Foo.prototype.bar = function bar() {};
(function bar() {/* ... */})();Examples of correct code for this rule with the "never" option:
js
/* func-names: ["error", "never"] */
Foo.prototype.bar = function() {};
(function() {/* ... */})();generators
Examples of incorrect code for this rule with the "always", { "generators": "as-needed" } options:
js
/* func-names: ["error", "always", { "generators": "as-needed" }] */
(function*() {/* ... */})();Examples of correct code for this rule with the "always", { "generators": "as-needed" } options:
js
/* func-names: ["error", "always", { "generators": "as-needed" }] */
const foo = function*() {};Examples of incorrect code for this rule with the "always", { "generators": "never" } options:
js
/* func-names: ["error", "always", { "generators": "never" }] */
const foo = bar(function* baz() {});Examples of correct code for this rule with the "always", { "generators": "never" } options:
js
/* func-names: ["error", "always", { "generators": "never" }] */
const foo = bar(function*() {});Examples of incorrect code for this rule with the "as-needed", { "generators": "never" } options:
js
/* func-names: ["error", "as-needed", { "generators": "never" }] */
const foo = bar(function* baz() {});Examples of correct code for this rule with the "as-needed", { "generators": "never" } options:
js
/* func-names: ["error", "as-needed", { "generators": "never" }] */
const foo = bar(function*() {});Examples of incorrect code for this rule with the "never", { "generators": "always" } options:
js
/* func-names: ["error", "never", { "generators": "always" }] */
const foo = bar(function*() {});Examples of correct code for this rule with the "never", { "generators": "always" } options:
js
/* func-names: ["error", "never", { "generators": "always" }] */
const foo = bar(function* baz() {});How to use
To enable this rule in the CLI or using the config file, you can use:
bash
oxlint --deny func-namesjson
{
"rules": {
"func-names": "error"
}
}