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.
Example configuration:
{
"func-names": ["error", "as-needed", { "generators": "never" }]
}Examples
Examples of incorrect code for this rule:
/* func-names: ["error", "always"] */
Foo.prototype.bar = function () {};
const cat = { meow: function () {} };
(function () {
/* ... */
})();
export default function () {}Examples of correct code for this rule:
/* 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:
/* 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:
/* 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:
/* func-names: ["error", "never"] */
Foo.prototype.bar = function bar() {};
(function bar() {
/* ... */
})();Examples of correct code for this rule with the "never" option:
/* func-names: ["error", "never"] */
Foo.prototype.bar = function () {};
(function () {
/* ... */
})();generators
Examples of incorrect code for this rule with the "always", { "generators": "as-needed" } options:
/* func-names: ["error", "always", { "generators": "as-needed" }] */
(function* () {
/* ... */
})();Examples of correct code for this rule with the "always", { "generators": "as-needed" } options:
/* func-names: ["error", "always", { "generators": "as-needed" }] */
const foo = function* () {};Examples of incorrect code for this rule with the "always", { "generators": "never" } options:
/* func-names: ["error", "always", { "generators": "never" }] */
const foo = bar(function* baz() {});Examples of correct code for this rule with the "always", { "generators": "never" } options:
/* func-names: ["error", "always", { "generators": "never" }] */
const foo = bar(function* () {});Examples of incorrect code for this rule with the "as-needed", { "generators": "never" } options:
/* 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:
/* func-names: ["error", "as-needed", { "generators": "never" }] */
const foo = bar(function* () {});Examples of incorrect code for this rule with the "never", { "generators": "always" } options:
/* func-names: ["error", "never", { "generators": "always" }] */
const foo = bar(function* () {});Examples of correct code for this rule with the "never", { "generators": "always" } options:
/* func-names: ["error", "never", { "generators": "always" }] */
const foo = bar(function* baz() {});Configuration
The 1st option
type: "always" | "as-needed" | "never"
"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.
The 2nd option
This option is an object with the following properties:
generators
type: "always" | "as-needed" | "never"
Configuration for generator function expressions. If not specified, uses the primary configuration.
Accepts always, as-needed, or never.
Generator functions are those defined using the function* syntax.
function* foobar(i) {
yield i;
yield i + 10;
}How to use
To enable this rule using the config file or in the CLI, you can use:
{
"rules": {
"func-names": "error"
}
}import { defineConfig } from "oxlint";
export default defineConfig({
rules: {
"func-names": "error",
},
});oxlint --deny func-namesVersion
This rule was added in v0.7.0.