no-negated-condition

When both branches are there, a negated condition makes the else a double negative: "if not logged in .. otherwise ..". Swapping the branches removes the negation and says the same thing.

The rule looks at conditions of the form !x, a != b and a !== b. An if without else is fine, and so is one followed by else if.

With an oxlint config, --fix removes the negation and swaps the branches.

Configure

Off by default. To turn it on:

[lint.rules]
"no-negated-condition" = "error" # or "warn"

Examples

Reported:

if (!user) {
  redirect("/login");
} else {
  render(user);
}

const label = count !== 1 ? "items" : "item";

Not reported:

if (user) {
  render(user);
} else {
  redirect("/login");
}

const label = count === 1 ? "item" : "items";

if (!user) {
  redirect("/login");
}

if (!user) {
  redirect("/login");
} else if (user.isAdmin) {
  renderAdmin(user);
}