EC
TS1198
TypeScriptERRORNotableSyntaxHIGH confidence

An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1198): An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive.. This diagnostic is emitted by the TypeScript compiler when an extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive..

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

TypeScript compiler reports TS1198 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1198
// An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive.

expected output

error TS1198: An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive.

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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