func-names

A callback written as function () {} shows up as <anonymous> in stack traces and profiles. When several callbacks are involved, you can't tell from the trace which one failed.

Arrow functions and methods aren't checked.

Configure#

Off by default. To turn it on:

[lint.rules]
"func-names" = "error" # or "warn"

Every option, set to its default. The ones that are commented out are unset by default.

[lint.rules]
"func-names" = [
  "error",
  "always", # "always", "as-needed" or "never"
  {
    # generators = <"always", "as-needed" or "never">,
  },
]

Examples#

button.addEventListener("click", function () {
  save();
});

export default function () {
  return "ready";
}

button.addEventListener("click", function onClick() {
  save();
});

button.addEventListener("blur", () => save());

Options#

[lint.rules]
func-names = ["error", "as-needed"]

A second option, { "generators": "always" | "as-needed" | "never" }, sets the same choice for generator functions only. Without it, generators follow the first option.

"as-needed"#

A function that's assigned to a variable or used as the value of an object key takes that name, so it doesn't need its own:

const save = function () {};

const handlers = {
  close: function () {},
};

With "always", both are reported:

const save = function () {};

const handlers = {
  close: function () {},
};

A callback doesn't get a name that way, and neither does a function assigned to object.property. Both are still reported:

items.forEach(function (item) {
  render(item);
});

handlers.open = function () {};

"never"#

items.forEach(function renderItem(item) {
  render(item);
});

items.forEach(function (item) {
  render(item);
});

const factorial = function fact(n) {
  return n <= 1 ? 1 : n * fact(n - 1);
};

generators#

run(function* () {
  yield 1;
});