Reference-Educational Template

Purpose

This template demonstrates educational content delivery with concept explanation, examples, and anti-patterns.

Use this template when:

• Teaching concepts or design patterns
• Explaining language features
• Demonstrating best practices
• Showing common mistakes to avoid

Workflow

Phase 1: Explain Concept

Phase 2: Show Examples

Phase 3: Demonstrate Patterns

Phase 4: Highlight Pitfalls

Progressive Disclosure

Core content (this file):

• Concept explanation
• Basic examples
• When to use guidance

Detailed examples (references/):

• @references/type-guard-examples.md - Complete pattern demonstrations
• Advanced techniques and edge cases

Example Usage

<explain>
Type guards are TypeScript constructs that narrow types within conditional blocks.
They allow the compiler to understand type refinement based on runtime checks.

Why: TypeScript needs runtime evidence to narrow union types safely.
When: Use when working with union types or unknown data.
</explain>

<examples>
Basic typeof guard:
```typescript
function process(value: string | number) {
  if (typeof value === "string") {
    return value.toUpperCase();
  }
  return value.toFixed(2);
}

See Also

• @references/type-guard-examples.md - Comprehensive type guard patterns