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Severity: warning
Category: Control flow
Stage: Stage 1

Description

A return, throw, break, or continue statement unconditionally transfers control away from the current block. Any statement in the same block that follows one of these terminators will never execute at runtime. SJS reports each such unreachable statement to help developers catch dead code, misplaced logic, or early-return bugs.

The warning is anchored to the first unreachable statement; subsequent unreachable statements in the same block are also warned but do not cascade into nested blocks.

Example

// ✗ warning
function clamp(n: number, min: number, max: number): number {
  if (n < min) {
    return min
    console.log("clamped low")   // SJS-W009 — after return
  }
  return Math.min(n, max)
  return max                     // SJS-W009 — after return
}
// ✗ warning
for (let i = 0; i < 10; i++) {
  if (i === 5) {
    break
    i++                          // SJS-W009 — after break
  }
}

Suppression / Fix

Remove or relocate the unreachable statement:

// ✓ correct
function clamp(n: number, min: number, max: number): number {
  if (n < min) {
    console.log("clamped low")
    return min
  }
  return Math.min(n, max)
}

If the statement was intended as a debugging guard that should only run conditionally, wrap it in its own if block instead of placing it after the terminator.

Related codes

  • SJS-W003 — unreachable match arm covered by an earlier arm
  • SJS-W008 — implicit switch fallthrough between non-empty case clauses
Documentation