The cost-based optimizer is the component of a database that decides how to execute a query. It does not guess. It reads statistics about the tables, columns, and indexes involved, estimates how many rows each step of the plan will produce, and assigns a cost to every candidate plan. The plan with the lowest cost…
Intro The Core Web Stack path covers the essential foundation required to design, build, and deploy modern web applications. From understanding basic web protocols and standard client-side markup to building REST APIs, managing source code with version control, and handling package dependencies, this roadmap provides a complete developer toolkit. Tutorials
Every package you install with npm lands in one of two places in your package.json: dependencies or devDependencies. The distinction is not cosmetic. It determines whether the package is installed when you build for production, whether it is shipped in your deployment artifact, and whether your production server can actually run the code after deployment….
The package.json file is the single most important file in a Node.js project. It is the manifest that tells npm what the project is, what it depends on, and how to run it. Every npm install, npm run, and npm publish reads this file. The npm documentation describes it as “the whole interface” to npm—without…
Every Node.js project begins with a package.json file. It is the manifest that records the project’s name, its version, its scripts, and the dependencies it needs. Creating that file by hand is possible but error-prone: a missing name, a version that does not follow semantic versioning, or a typo in the scripts key produces a…
Node.js and npm are installed together, but they are versioned separately. Node.js ships with a specific npm version bundled into each release—Node.js 24.19.0 includes npm 11.17.0, for example—and npm releases new versions more frequently than Node.js does . This means the npm you have is not necessarily the latest npm, even if your Node.js is…
npm is the package manager for the Node JavaScript platform. Its job is to put modules in place so that Node.js can find them, and to manage the dependency conflicts that arise when different packages require different versions of the same library . The name originally stood for “Node Package Manager,” and it refers to…
CORS is not a security feature. It is a browser-enforced relaxation of the same-origin policy, and the server’s only job is to return the headers that tell the browser whether a cross-origin response is allowed to be read . The browser sends the request regardless; if the response lacks the correct Access-Control-Allow-Origin header, the browser…
Authentication answers who is making the request. Authorization answers what that identity is allowed to do. The two dominant models for that decision are Role-Based Access Control and Attribute-Based Access Control. RBAC assigns permissions to roles, and users acquire permissions by being assigned to roles. ABAC evaluates policies against attributes of the user, the resource,…
OAuth 2.0 and OpenID Connect are often mentioned together, but they answer different questions. OAuth 2.0 is an authorization framework: it lets an application obtain limited access to a protected resource on behalf of a user, without the user sharing their password with the application . OpenID Connect is an authentication layer built on top…