list of programming languages
A GROUP BY clause with a single set of columns produces one row per distinct combination of those columns. That is the standard aggregation behavior, and it answers a specific question: “what is the total for each group?” But analytical queries often need more than one answer at once. A report might need the total…
A JavaScript library written in plain JavaScript ships no types. When a TypeScript consumer imports it, the compiler sees any for every export, and the type safety is lost. The solution is a type declaration file — a .d.ts file that describes the library’s shape — and the ecosystem’s mechanism for distributing those files is…
A Zone is an execution context that wraps asynchronous callbacks and intercepts the events that happen inside them. The zone can catch the errors the callback throws, the uncaught errors the future rejects, the timers the callback schedules, and the print calls the callback makes. The zone is the mechanism the frameworks use to bind…
The browser gives JavaScript more than just the DOM. It exposes a set of Web APIs — tools the environment provides on top of the language — for talking to servers, storing data, and scheduling work. Three of them cover the vast majority of what you’ll do in real code: fetch for network requests, localStorage…
Node.js is single-threaded by design, but it is not limited to a single process. The child_process module lets you spawn additional processes from your Node.js application, whether they are system commands, external binaries, or other Node.js scripts. This is the mechanism behind build tools, CLI wrappers, worker pools, and any situation where the work is…
Shared mutable state is the classic source of concurrency bugs. Two threads incrementing the same counter without coordination can produce a wrong total because the increment is three operations—read, add, write—and the threads can interleave arbitrarily . Rust does not eliminate shared state, but it makes the dangerous parts impossible to ignore. The Mutex<T> type…
A Common Table Expression is a named temporary result set that exists for the duration of a single query. It is defined with the WITH keyword, and it can be referenced by name anywhere in the query that follows. The CTE is not a view — it is not stored in the database schema —…
A Promise is a value that will be available later. An async function returns a Promise, and await unwraps the Promise’s value. The JavaScript runtime has had these for years, and TypeScript’s types for them are precise: Promise<T> is the type of a Promise that resolves to T, async functions return Promise<T> automatically, and await…
Dart zones are one of the most misunderstood features in the Dart language. They look simple on the surface—a way to run code in a special context—but they underpin almost every serious logging, error-handling, and observability pattern in production Dart and Flutter applications. This chapter focuses on the advanced use of zones for logging, diagnostics,…
Design patterns are reusable solutions to common problems. They’re not algorithms — they’re templates for structuring code that have proven themselves across many projects. In JavaScript, some patterns are more relevant than others because the language handles certain things natively. The patterns worth knowing in JavaScript fall into three groups: creational (how to make objects),…