EC
TS1263
TypeScriptERRORNotableSyntaxHIGH confidence

Declarations with initializers cannot also have definite assignment assertions.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1263): Declarations with initializers cannot also have definite assignment assertions.. This diagnostic is emitted by the TypeScript compiler when declarations with initializers cannot also have definite assignment assertions..

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

TypeScript compiler reports TS1263 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1263
// Declarations with initializers cannot also have definite assignment assertions.

expected output

error TS1263: Declarations with initializers cannot also have definite assignment assertions.

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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