EC
TS18042
TypeScriptERRORNotableTypeHIGH confidence

'X' is a type and cannot be imported in JavaScript files. Use 'X' in a JSDoc ...

Production Risk

Build will fail; resolve before shipping.

What this means

A TypeScript diagnostic (TS18042): 'X' is a type and cannot be imported in JavaScript files. Use 'X' in a JSDoc type annotation.. This diagnostic is emitted by the TypeScript compiler when 'X' is a type and cannot be imported in JavaScript files. Use 'X' in a JSDoc type annotation..

Why it happens
  1. 1Incorrect TypeScript syntax or type usage
  2. 2Type mismatch between declared and actual value
How to reproduce

TypeScript compiler reports TS18042 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS18042
// 'X' is a type and cannot be imported in JavaScript files. Use 'X' in a JSDoc type annotation.

expected output

error TS18042: 'X' is a type and cannot be imported in JavaScript files. Use 'X' in a JSDoc type annotation.

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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