TS8004
TypeScriptERRORNotableStrictHIGH confidence
Type parameter declarations can only be used in TypeScript files.
Production Risk
Build will fail; resolve before shipping.
What this means
A strict mode error (TS8004): Type parameter declarations can only be used in TypeScript files.. This diagnostic is emitted by the TypeScript compiler when type parameter declarations can only be used in TypeScript files..
Why it happens
- 1Incorrect number or type of generic type arguments
How to reproduce
TypeScript compiler reports TS8004 during type checking.
trigger — this will error
trigger — this will error
// Triggers TS8004 // Type parameter declarations can only be used in TypeScript files.
expected output
error TS8004: Type parameter declarations can only be used in TypeScript files.
Fix
Address the TypeScript diagnostic
WHEN When this error is reported by the compiler
Address the TypeScript diagnostic
// Run the TypeScript compiler for details: npx tsc --noEmit // Use the TypeScript playground to test your code: // https://www.typescriptlang.org/play
Why this works
Review the full error message and location; the TypeScript handbook provides guidance on each error category.
Sources
Official documentation ↗
TypeScript Compiler Diagnostics
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