Easy everything in TypeScript & Web APIs
First compilerOptions to set after tsc --init
Enable strict for full type safety, set target and module to match the runtime, and choose outDir/rootDir or moduleResolution; each tightens checks or aligns output.
Matt Pocock's Free React TypeScript Tutorial
Matt Pocock's free React TypeScript tutorial teaches typing for hooks, props, events via hands-on exercises. Covers ComponentProps, useRef, and reading React's type defs to debug errors. Bookmark this if your team is adopting TypeScript.
Matt Pocock Tutorial Covers Ten TypeScript Errors
Cryptic TypeScript errors waste hours. Matt Pocock's new tutorial isolates ten common messages from "Type Not Assignable" to "Property Does Not Exist" in interactive exercises. Clone the repo or use Gitpod to build debugging instincts instead of guessing.
Chrome 136 cuts JS startup 630ms with compile hints
Chrome 136 ships Explicit Compile Hints, cutting parse and compile times by 630ms in V8 tests. The //# allFunctionsCalledOnLoad comment triggers eager background compilation for entire files, avoiding main-thread bottlenecks.
Chrome M137 Ships Speculative Deopts and Inlining for Wasm
Chrome M137 adds speculative inlining and deoptimization to V8's WebAssembly engine, cutting Dart microbenchmarks by over 50%. It targets WasmGC, making Java, Kotlin, and Dart faster using JS-style JIT assumptions. Benchmark WasmGC apps on M137 now.
V8 doubles JSON.stringify speed with side-effect-free fast path
V8 doubled JSON.stringify speed with a side-effect-free fast path. Every network and storage serialization of plain objects gets faster with zero code changes. Check your profiles if JSON encoding shows up hot.
Mozilla WAICT Verifies Web App JavaScript in Nightly
WAICT in Firefox Nightly binds client code to public manifests so browsers reject unlogged JavaScript. This stops compromised servers from silently injecting malicious code into encrypted web apps like Signal. Test it at waict.dev.
Claude Mythos Cracks Firefox Bugs Fuzzing Missed
Claude Mythos Preview found 20-year-old XSLT and JIT bugs in Firefox that survived years of fuzzing. Mozilla shows AI now catches sandbox escapes and memory corruption. Add LLM security scanning to hardening workflows before attackers adopt them.
Firefox 151 adds Web Serial for desktop
Firefox 151 for Desktop adds Web Serial support for compatible hardware. It gives web-based device tools another browser to support. Check permissions, operating-system support and actual devices before removing a native fallback.
How do you write a minimal dom-utils.d.ts for a JS function?
Tests bridging untyped JavaScript into TypeScript via ambient module declarations. A strong answer declares a module matching the file path and exports the function with a typed signature. Red flag: suggesting rename to .ts or using any.
How do you add TypeScript types for a library without bundled types?
This tests the DefinitelyTyped @types workflow. Install @types/package as a dev dependency via npm or yarn, skipping it when the library already bundles .d.ts files. A red flag is suggesting manual declarations or extra tooling before checking DefinitelyTyped.
What is tsconfig strict, and which sub-flag to relax for legacy?
Tests strict as a master switch and migration pragmatism. Strong answers name strictNullChecks or noImplicitAny as the first to relax in legacy code, trading null-safety for fewer errors. Red flag: disabling strict entirely instead of a targeted sub-flag.
Write a TypeScript async/await function that requests webcam access and handles errors
This tests async/await error handling for getUserMedia and stream attachment. A good answer uses try/catch, sets video.srcObject, and branches on NotAllowedError and NotFoundError. A red flag is omitting catch or using src instead of srcObject.
Get canvas 2D context and draw a filled circle
This tests Canvas API coordinates and context acquisition. A strong answer selects the canvas, calls getContext("2d"), uses path functions for circles, sets color style, and fills. A red flag is ignoring the top-left origin or using SVG instead.
How do you programmatically play, pause, and dynamically set a video source?
Your grasp of HTMLMediaElement's imperative API and the play() Promise. Query the video, attach play() and pause() to buttons, and set src or swap source children then call load(). Treating play() as synchronous or changing src without load().
What is a Service Worker's role and key PWA capability?
Tests understanding of the Service Worker as a network proxy and its core PWA benefit. A strong answer states it intercepts requests as a proxy and enables offline use via granular caching. Red flag: confusing it with Web Workers or DOM manipulation.
Which Web API offloads expensive work from the main UI thread?
Cite Web Workers, instantiate new Worker(url), and communicate via postMessage and onmessage.
Programmatically change SPA URL without reload and what is state for?
This tests History API fluency. Answer: use pushState or replaceState to change the URL silently; the state object is serializable data tied to the history entry, surfaced through popstate on back or forward navigation.
How do you store and retrieve a TypeScript object in localStorage?
This tests your knowledge of Web Storage string constraints and JSON serialization. A strong answer covers JSON.stringify on write, JSON.parse on read, and typing the result with a TypeScript interface.
What is the core difference between localStorage and sessionStorage?
SessionStorage dies with its tab; localStorage survives restarts and shares across tabs. Example: checkout form versus theme preference.
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