Web Developer Dictionary

Jamstack (JavaScript, APIs, Markup) is an architectural approach to the web: pre-generated static HTML files served via CDN, with dynamic functionality delivered through APIs. No traditional server-side rendering on every request. Key principles Pre-rendering — HTML is generated at build time, not at request time Decoupling — frontend and backend are separate, communicating via API CDN-first — static assets served from edge nodes close to the user Benefits Maximum speed — files from CDN, no server TTFB Security — no server to attack Scalability — CDN scales automatically When it does not fit Personalised content, real-time data, large e-commerce with millions of SKUs — where pre-rendering is impractical. Solved via ISR (Incremental Static Regeneration) or hybrid rendering. Popular solutions Next.js, Nuxt, Astro, Gatsby + Netlify/Vercel/Cloudflare Pages.

JOIN is a SQL operator that combines rows from two or more tables based on a matching condition. A proper JOIN replaces dozens of separate queries and is fundamental to working efficiently with relational data.JOIN typesINNER JOIN — returns only rows where the condition is met in both tables. Most commonLEFT JOIN — all rows from the left table + matching rows from the right (or NULL if no match)RIGHT JOIN — the mirror of LEFT JOIN. Rarely usedFULL OUTER JOIN — all rows from both tables, NULL where there is no matchExampleSELECT u.name, o.total FROM users u INNER JOIN orders o ON o.user_id = u.id WHERE o.status = 'paid';PerformanceJOINs on indexed columns (typically foreign keys) are fast. JOINs on unindexed fields are expensive. EXPLAIN shows whether an index is being used.

JSON (JavaScript Object Notation) is a text-based data interchange format and a subset of JavaScript. Human-readable, compact, supported by every programming language. The de facto standard for REST APIs and configuration files.Data types{ "string": "hello", "number": 42, "float": 3.14, "boolean": true, "null": null, "array": [1, 2, 3], "object": { "key": "value" } }PHP$json = json_encode($data); // array → string $data = json_decode($json, true); // string → array // Check for errors: if (json_last_error() !== JSON_ERROR_NONE) { ... }JSON vs XMLJSON: shorter, simpler to read and parse. XML: supports attributes, namespaces, schemas (XSD), better suited to complex documents. On the web, JSON has won.JSON SchemaA specification for describing and validating the structure of a JSON document. The equivalent of XSD for XML.

JWT (JSON Web Token) is a compact, self-contained token for transmitting information between parties as a signed JSON object. Unlike sessions, the server stores no state — all information lives in the token itself.StructureA JWT consists of three Base64-encoded parts separated by dots: header.payload.signature. The header specifies the signing algorithm. The payload contains claims — arbitrary data (user_id, roles, exp). The signature lets the server verify the token has not been tampered with.When to useStateless APIs — the server needs no database to validate a requestMicroservices — the token is verified independently in each servicePitfallsJWTs cannot be revoked before expiry without a blacklist. Store them in an httpOnly cookie, not localStorage — this protects against XSS. Set a short exp (15–60 min) and use refresh tokens.