Front‑End Essentials: Optimizing Large File Uploads, Cutting If‑Else, and HTTP/3/Deno Updates

Technical Knowledge

Optimizing Large File Uploads

Compute the file's MD5 hash on the client using the spark-md5 library.

Track upload status for each slice to enable retry on failure.

Slice the file with Blob.slice (the File object inherits this method).

Upload each slice via an AJAX request that registers an onProgress listener to report per‑slice progress.

On successful upload of all slices, send a final request containing the overall MD5 value so the server can verify integrity and merge the parts, preventing tampering.

Eliminating Excessive if‑else Chains

Table‑driven dispatch: build a Map<String, Runnable> where the key is a condition value and the value is the handler to invoke. Works well for simple type checks.

Responsibility‑chain pattern: chain handler objects; each decides to process the request or pass it to the next, flattening nested conditionals.

Annotation‑driven execution: annotate methods with metadata that describes the condition under which they should run, then reflectively invoke the matching method.

Event‑driven mapping: map a single event to multiple listeners, allowing one‑to‑many relationships unlike the one‑to‑one mapping of table‑driven dispatch.

Finite‑state‑machine (FSM): treat the combination of current state and incoming event as a lookup key in a transition table; after handling, transition to the next state.

Utility‑based null checks: use Optional to centralize non‑null validation.

Assert utilities: provide concise validation assertions similar to Optional.

Polymorphism: move conditional branches into subclass overrides, removing repeated if‑else blocks from a single location.

Weekly News

HTTP/3 Principles and Practice

In 2013 Google created QUIC (Quick UDP Internet Connections), a UDP‑based transport protocol intended to replace TCP for faster web delivery. The IETF later renamed HTTP over QUIC to HTTP/3. Reference URL: https://mp.weixin.qq.com/s/7tKgSmkMWHdIyvrTWJE8sg

Deno 1.0 Overview

Deno 1.0 was released on 2020‑05‑13. It is authored by the original creator of Node.js and built with Rust + Tokio, embedding the V8 engine with native TypeScript support. Deno omits package.json and node_modules , providing many built‑in features that in Node.js typically require third‑party npm packages. Reference URL: https://mp.weixin.qq.com/s/85x4uep6SAZ9v_AR2hqv4w