/obsidian

Type Safety

Type safety is essential for reliable Obsidian plugins. Use proper type narrowing and avoid unsafe type casts.

Avoid Type Casting to TFile/TFolder

Rule: obsidianmd/no-tfile-tfolder-cast

❌ INCORRECT:

const file = abstractFile as TFile;
const folder = <TFolder>abstractFile;

✅ CORRECT:

if (abstractFile instanceof TFile) {
  // TypeScript now knows it's a TFile
  const file = abstractFile;
}

if (abstractFile instanceof TFolder) {
  const folder = abstractFile;
}

Rationale: Type casting bypasses type safety. Use instanceof for safe type narrowing.

Avoid TypeScript any

Rule: Type safety best practice

❌ INCORRECT:

function processData(data: any) {
  return data.value;
}

✅ CORRECT:

// Use specific types
function processData(data: FileData) {
  return data.value;
}

// Or use unknown for truly unknown data
function processData(data: unknown) {
  if (typeof data === 'object' && data !== null && 'value' in data) {
    return (data as { value: string }).value;
  }
}

Rationale: any bypasses type checking. Use specific types or unknown for type safety.

Prefer const and let over var

Rule: Official guidelines (TypeScript best practice)

❌ INCORRECT:

var count = 0;
var settings = {};

✅ CORRECT:

let count = 0;
const settings = {};

Rationale: Use const for values that won't be reassigned and let for values that will. Avoid var for better scoping and fewer bugs.