react/no-object-type-as-default-prop

A default value in the parameter list is evaluated again on every render. users = [] creates a new array each time, so the prop never equals its value from the last render. A useEffect or useMemo that depends on it runs on every render, and a child wrapped in memo renders again every time. If the effect sets state, the component renders in a loop.

The rule checks function components that destructure their props in the parameter list. It reports these defaults: an object, an array, a function, a class, a new expression, a regular expression, a JSX element, and a call to Symbol(). Strings, numbers, booleans, and variables are fine.

Configure#

Off by default. To turn it on:

[lint.rules]
"react/no-object-type-as-default-prop" = "error" # or "warn"

Examples#

function UserList({ users = [], onSelect = () => {} }) {
  return <List items={users} onSelect={onSelect} />;
}

const noUsers = [];
const ignore = () => {};

function UserList({ users = noUsers, onSelect = ignore, limit = 10 }) {
  return <List items={users.slice(0, limit)} onSelect={onSelect} />;
}

The rule skips a function that isn't a component:

function sortUsers({ users = [] }) {
  return users.toSorted((a, b) => a.name.localeCompare(b.name));
}