Substrate

@studnicky/v8/switch-statements ​

Requires each switch case to delegate rather than contain inline multi-statement logic. A case body wrapped in a block is reported, as is an unwrapped case with two or more statements after ignoring one trailing break, continue, or return. A single delegated call or return, optionally followed by one of those terminators, is allowed.

This is a readability and structure rule, not a V8-performance rule. Proven with node --allow-natives-syntax --print-bytecode --print-bytecode-filter=<fn> on a 20-case integer switch: a version with one-line delegating case bodies and a version with multi-statement inlined case bodies both compile to the identical dispatch opcode SwitchOnSmiNoFeedback [0], [20], [0] on Node v24 — case-body size has zero effect on dispatch strategy. The message carries no v8Optimization/ prefix because it protects no V8 mechanism.

The rule applies regardless of case count and is independent of the switch-versus-dispatch-map choice max-switch-cases enforces at scale: a small switch below that threshold still must keep each case a one-line delegation to a static class method, not an inline block. max-switch-cases carries the proven performance claim about case count; this rule addresses case-body size only.

Fixable: No · Options: No · Suggested severity: error

✗ Incorrect ​

ts
switch (action) {
  case 'start': {
    const result = initialize();
    return result;
  }
  case 'stop':
    cleanup();
    audit();
    break;
}

✓ Correct ​

ts
switch (action) {
  case 'start': return initialize();
  case 'stop':
    cleanup();
    break;
  default: return undefined;
}
ts
function stop(): void {
  cleanup();
  audit();
}

switch (action) {
  case 'stop':
    stop();
    break;
}