Browser

@alexify/metaschema runs in the browser without configuration. Nothing in the package touches a Node.js builtin except the file write behind saveTypes, which lives in src/runtime/node.js.

Bundlers that honor the browser field or the browser export condition (Vite, webpack, esbuild, Rollup with the node-resolve plugin) pick browser.js and swap src/runtime/node.js for its browser twin automatically.

import { Schema } from '@alexify/metaschema';

const form = Schema.from({ email: 'string', age: '?number' });
const { valid, errors } = form.check({ email: 'marcus@example.com', age: 42 });

Everything works the same as in Node.js, with one exception: saveTypes of the generators subpath has no file system to write to, so it returns a rejected promise. Read toTypeScript(model) and send it wherever you need instead.

Bundling and minification are safe: metaschema recognises its own schemas, fields and results by a global symbol brand (Symbol.for), not by class names, so a bundler that renames a class or a minifier that mangles it cannot switch validation off. The repository's tests/unit/bundle.test.js builds both entry points with esbuild, minified and not, and validates through the result.

The core entry is 21.3 KB min+gzip in either environment, and CI keeps it under 22 KB; the @alexify/metaschema/generators subpath (JSON Schema, TypeScript) adds 7.7 KB where it is imported, under a budget of 8 KB, the @alexify/metaschema/compile subpath (the JIT backend) 4.3 KB, under 5 KB, the @alexify/metaschema/model subpath (snapshots, diff, samples, merge, inference) 12.7 KB, under 13 KB, the @alexify/metaschema/stream subpath (records and streams) 0.9 KB, under 1.5 KB, the @alexify/metaschema/formats subpath (string formats) 3.9 KB, under 5 KB, the @alexify/metaschema/derive subpath (pick, omit, partial) 2.2 KB, under 2.5 KB, the @alexify/metaschema/coerce subpath (the converters of coercion) 1.9 KB, under 2 KB, and the @alexify/metaschema/mongodb subpath 3.6 KB on top of ./coerce, under 4 KB. A client that only reads schemas imports @alexify/metaschema/definition instead of the core: 10.3 KB, under 11 KB. pnpm size in the repository prints the exact numbers. The package says in sideEffects that only its entries have side effects (loading the core installs validation into the classes, so import '@alexify/metaschema' for that alone is kept): no subpath registers on import, so a bundler may drop a subpath an ESM program imports and never calls (a CommonJS require of a subpath keeps it whole: there is no tree shaking of one format or one converter out of its table).

Content Security Policy

The JIT backend builds a check with new Function, which a Content Security Policy without 'unsafe-eval' forbids. The subpath probes it once (canEval()) and keeps the closure backend where it is forbidden: compile returns { accelerated: false }, register() installs nothing, and check behaves exactly as before, at the speed of the closures. Nothing in the core entry evaluates code, so a policy without 'unsafe-eval' is the right default; add the subpath where the policy allows it and let the probe decide, or pass { jit: false } where generated code is not wanted at all.