Know How to Tell Whether a Symbol Is in Type Space or Value Space

Overview

Every symbol in TypeScript exists in type space, value space, or both.

The same name can refer to completely different things depending on context. Understanding this distinction is essential for reading TypeScript code correctly.

When to Use This Skill

• Debugging confusing type errors
• Understanding class vs interface behavior
• Using typeof correctly
• Destructuring with type annotations
• Understanding enum behavior

The Iron Rule