Be Consistent in Your Use of Aliases

Overview

If you create an alias, use it consistently.

When you assign an object property to a variable, you create an alias. TypeScript tracks them separately, so narrowing one doesn't narrow the other. Choose one and stick with it.

When to Use This Skill

• Type narrowing isn't working as expected
• Using both a variable and its source property
• Property checks not affecting aliased variables
• Refinements being "lost" after function calls

The Iron Rule