When checking for null or undefined values, prefer the concise `!= null` comparison over explicit checks or array-based methods. This pattern effectively handles both null and undefined while preserving other falsy values like `false`, `0`, or empty strings.
When checking for null or undefined values, prefer the concise != null comparison over explicit checks or array-based methods. This pattern effectively handles both null and undefined while preserving other falsy values like false, 0, or empty strings.
The != null pattern is more readable and performant than alternatives:
// Preferred: Concise and clear
const hasCachedData = () => options.getCachedData!(key) != null
// Avoid: Verbose explicit checks
const hasCachedData = () => {
const data = options.getCachedData!(key)
return data !== null && data !== undefined
}
// Avoid: Array-based inclusion checks
const hasCachedData = () => ![null, undefined].includes(options.getCachedData!(key) as any)
For cases requiring additional type safety, combine null checks with type validation:
// Good: Null check with type validation
if (!rawVersion || typeof rawVersion !== 'string') {
return
}
// Good: Explicit equality for specific values
if (result === true) {
// Handle confirmed true, not just truthy
}
This approach maintains null safety while keeping code concise and avoiding unnecessary complexity in most common scenarios.
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