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Sarj Code Standards

prefer-switch-for-repeated-equality

Prefer switch over long if/else-if chains that compare one value for strict equality.

preferSwitch Rule source Tests Catalog JSON

Why

A switch makes finite dispatch cases visually uniform and easier to extend without duplicating the discriminant.

Fix

Replace three or more strict-equality branches over the same discriminant with a switch; keep if statements for ranges, guards, and heterogeneous predicates.

Examples

Before — flagged Use native identifier identity
src/dispatch.ts
function probe(kind) {
  if (kind === "a") return 1;
  else if (kind === "b") return 2;
  else if (kind === "c") return 3;
  return 0;
}
console.log(JSON.stringify(["a", "b", "c", "d"].map(probe)));
After — preferred Use native identifier identity
src/dispatch.ts
function probe(kind) {
  const other = "other";
  if (kind === "a") return 1;
  else if (other === "b") return 2;
  else if (kind === "c") return 3;
  return 0;
}
console.log(JSON.stringify(["a", "b", "c", "d"].map(probe)));
Before — flagged Avoid repeating the discriminant
src/render.ts
function render(kind: string) {
  if (kind === "a") return "alpha";
  else if (kind === "b") return "beta";
  else if (kind === "c") return "gamma";
  return "unknown";
}
After — preferred Make finite dispatch explicit
src/render.ts
function render(kind: string) {
  switch (kind) {
    case "a":
      return "alpha";
    case "b":
      return "beta";
    case "c":
      return "gamma";
    default:
      return "unknown";
  }
}