```typescript
function slugifyHandle(input: string, maxLen: number = 40): string {
    const slug = input.toLowerCase()
        .replace(/[^a-z0-9]+/g, '-') // Replace non-alphanumeric runs with a hyphen
        .replace(/^-+|-+$/g, '');    // Trim hyphens from start/end
    return slug.length > maxLen ? slug.substring(0, maxLen).replace(/-+$/g, '') : slug;
}
```

This TypeScript function converts a string into a slug by lowercasing it, replacing non-alphanumeric runs with hyphens, trimming exterior hyphens, and optionally truncating it to a given maximum length, defaulting to 40 characters.