EC
TS1487
TypeScriptERRORNotableSyntaxHIGH confidence

Octal escape sequences are not allowed. Use the syntax 'X'.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1487): Octal escape sequences are not allowed. Use the syntax 'X'.. This diagnostic is emitted by the TypeScript compiler when octal escape sequences are not allowed. Use the syntax 'X'..

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

TypeScript compiler reports TS1487 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1487
// Octal escape sequences are not allowed. Use the syntax 'X'.

expected output

error TS1487: Octal escape sequences are not allowed. Use the syntax 'X'.

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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