is-blob

This is a single-purpose utility that does exactly one thing: checks if a value is a Blob object. The implementation is straightforward—it verifies the value is an object with the right prototype chain. In practice, it's been reliable for validating file uploads and handling binary data in browser environments where you need to distinguish Blobs from other object types.

From a security perspective, there's minimal attack surface here. No dependencies means zero supply chain risk, which is refreshing. The code doesn't throw exceptions on invalid input—just returns false—so there's no risk of error information leakage. The type checking is defensive and won't break if you pass null, undefined, or weird objects.

The main limitation is that it's browser-focused. If you're working in Node.js with buffers or streams, this won't help much. It also won't distinguish between Blob and File (which extends Blob), but that's usually fine since File instances are valid Blobs. For simple type guards in modern web applications, it does the job without bloat.

This is one of those micro-utilities that does exactly one thing with zero fuss. The API is literally `isBlob(value)` returning a boolean - you can't get more ergonomic than that. It handles edge cases properly, including null/undefined checks and proper instanceof detection that works across realms. TypeScript support is built-in with proper type guards, so your IDE understands that after `if (isBlob(x))`, x is typed as Blob.

The main practical consideration is whether you actually need this package. Modern environments support `instanceof Blob` and `value instanceof Blob` works fine in most cases. However, this package shines when dealing with cross-realm scenarios (iframes, workers) or when you want consistent behavior across environments. The package is ESM-only in v3.0.0, which aligns with modern standards but requires Node 12+ and may cause issues in legacy setups.

Documentation is minimal but sufficient - there's really not much to document. No surprises, no gotchas, just reliable detection. For what it does, it does well.

In practice, `is-blob` does exactly what it says with zero configuration. The API is a single function that returns a boolean, making it trivially easy to integrate. TypeScript support is first-class with proper type guards that narrow types correctly in conditional blocks. The package correctly handles edge cases like null, undefined, and Blob-like objects that aren't actual Blobs.

The main value proposition is cross-environment reliability. It handles nuances between browser and Node.js environments where Blob detection can be tricky due to different implementations. The source is tiny and tree-shakeable, adding negligible bundle weight. Error handling isn't really applicable here since it's a pure predicate function that never throws.

The documentation is minimal but sufficient—there's really not much to document for a single-purpose utility. You import it, call it with a value, and get a boolean back. IDE autocomplete works perfectly, and the TypeScript definitions make the intent crystal clear.