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Severity: warning
Category: dynamic type
Stage: Stage 0 (prototype)

Description

In --strict mode, every function parameter, variable declaration, and return position must carry an explicit type annotation. When an annotation is absent, SJS defaults the type to dynamic — but does so silently. This warning makes the implicit dynamic visible so the developer can either add a real annotation or write dynamic explicitly to signal the intent.

The warning is only emitted in --strict mode. In normal mode, unannotated positions are inferred without a warning.

Example

// ✗ warning
function add(a, b) {       // SJS-W001 on `a` and `b`
  return a + b
}

let result = add(1, 2)     // SJS-W001 on `result` (return type inferred as dynamic)

Suppression / Fix

Add explicit type annotations to every unannotated position:

// ✓ correct
function add(a: number, b: number): number {
  return a + b
}

let result: number = add(1, 2)

If interop with untyped JS code genuinely requires a dynamic position, annotate it explicitly so the warning is suppressed and the intent is documented:

// ✓ correct — intentional dynamic
function wrap(value: dynamic): dynamic {
  return value
}

Related codes

  • SJS-E004 — any is not a valid type in SJS; use unknown or dynamic instead
  • SJS-W002 — dynamic value assigned to a typed position without a narrowing check
Documentation