EC
TS1498
TypeScriptERRORNotableSyntaxHIGH confidence

Invalid syntax in decorator.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1498): Invalid syntax in decorator.. This diagnostic is emitted by the TypeScript compiler when invalid syntax in decorator..

Why it happens
  1. 1A decorator is applied incorrectly or to an unsupported target
  2. 2The 'experimentalDecorators' flag may need to be enabled
How to reproduce

TypeScript compiler reports TS1498 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1498
// Invalid syntax in decorator.

expected output

error TS1498: Invalid syntax in decorator.

Fix

Enable experimentalDecorators

WHEN Using legacy decorator syntax

Enable experimentalDecorators
// tsconfig.json
{
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

Why this works

Decorators require the 'experimentalDecorators' flag; TypeScript 5.0+ also supports the TC39 Stage 3 decorator proposal without the flag.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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