bun/no-useless-spread-fallback

Spreading false, null or undefined into an object does nothing. So the {} in ...(condition ? { a } : {}) isn't needed, and ...(condition && { a }) does the same thing with less code.

The rule checks spreads in object literals and in JSX attributes.

--fix-suggestions rewrites condition ? value : {} to condition && value.

Configure

Off by default. To turn it on:

[lint.rules]
"bun/no-useless-spread-fallback" = "error" # or "warn"

Every option, set to its default:

[lint.rules]
"bun/no-useless-spread-fallback" = ["error", {
  ignoreConditionsThatCall = [], # list of strings
}]

Examples

Reported:

const headers = {
  accept: "application/json",
  ...(apiKey ? { "x-api-key": apiKey } : {}),
};

const link = <a href={url} {...(external ? { target: "_blank" } : {})}>{label}</a>;

Not reported:

const headers = {
  accept: "application/json",
  ...(apiKey && { "x-api-key": apiKey }),
};

An empty object in the first branch is reported too, without a suggestion:

const query = { page, ...(showAll ? {} : { limit: 20 }) };

const query = { page, ...(!showAll && { limit: 20 }) };

Options

Use it for a function that a build tool only understands as the condition of ? :, such as a feature flag:

const routes = {
  home,
  ...(feature("ADMIN") ? { admin } : {}),
};