Setting the file. One moment.
Subchapter 1.158
references/FUNCTION_LIBRARY.mdMarkdown7 KBView on GitHub
Studio 2 editor only. This extension type works only on sites built in the Studio 2 editor. It does not run on Harmony, the classic Wix Editor or Wix Studio (Editor X), so do not offer it for those sites. Apps can’t use it: if
wix.config.jsonhas"projectType": "App", tell the user before building.
A function library bundles reusable functions the Wix editor and runtime can call — formatters, math helpers, data transformers, event handlers. It is a registered extensions.functionLibrary() extension, not a plain utility module: functions in utils.ts, helpers.ts or src/lib/ are invisible to the editor.
You MUST read FUNCTION_LIBRARY_SPEC.md before implementing a function library. It holds the manifest fields, DOM event types and type constraints; the data types are in DATA_TYPES.md.
Not done: Scaffold with the Wix CLI, from the project root:
npx wix generate --params '{"extensionType":"FUNCTION_LIBRARY","name":"<library-name>"}'name is kebab-case (e.g. car-formatting) — the CLI rejects spaces and uppercase. It derives the folder, type, id and the src/extensions.ts registration from it, and creates src/extensions/site/function-libraries/{library-name}/{library-name}.ts (a formatPrice stub) and {library-name}.extension.ts.
Not done: In {library-name}.extension.ts, add resources.moduleSpecifier (the scaffold omits it, see Hard Constraints) and set name to a Title Case display name (e.g. Car Formatting, max 100 chars) — the scaffold writes the kebab-case name there, and the editor lists the library under it
Not done: Install @wix/editor-react-types as a devDependency if not already present
Not done: Replace the formatPrice stub in {library-name}.ts with your named exports, and the formatPrice entry in the functions map with one entry per function (parameters, return type, async flag). Keep the CLI-generated id
moduleSpecifier sits directly under resources, next to client, not inside it. tsc does not catch a misplaced one:
resources: {
client: { /* generated, leave as is */ },
moduleSpecifier: '@/car-formatting',
},extensions comes from @wix/astro/builders/experimental (current scaffold) or @wix/custom-extensions (older scaffolds). Both work: keep the import the scaffold wrote. If tsc reports that functionLibrary does not exist on extensions, upgrade that package.
resources.moduleSpecifier to <moduleSpecifierPrefix><library-name> (e.g. @/car-formatting). <moduleSpecifierPrefix> is @/ by default, or the prefix the user gives you. Module specifiers are unique across all of Wix, not per app: an unprefixed name may already belong to another app, and the checkpoint then fails with Error during component specifier upsertmoduleSpecifier of a library that already exists — a registered module specifier cannot be renamed. The prefix rule applies to new libraries onlyfunctions map — a mismatch means the editor references a function that doesn’t exist at runtime. Named exports only, no export defaultbooleanValue — NOT boolean, which is a TypeScript primitive and not a valid dataTyperichText requires a RichText object from @wix/editor-react-types with text, html, and linkList; an HTML string is not one. For plain strings, declare text. See RichText valuesdataType or domEvent, and optional parameters come lastimport type { Text, NumberType, WebUrl } from '@wix/editor-react-types';
export function capitalize(text: Text): Text {
return text.charAt(0).toUpperCase() + text.slice(1).toLowerCase();
}
export function sum(numbers: NumberType[]): NumberType {
return numbers.reduce((acc, num) => acc + num, 0);
}
export async function fetchData(url: WebUrl): Promise<Text> {
const response = await fetch(url);
return await response.text();
}
export function logEvent(eventName: Text): void {
console.log(`[event] ${eventName}`);
}@wix/editor-react-types — Text, NumberType, BooleanValue, WebUrl, etc. — these match the runtime format Wix provides. Other types are exported under their PascalCase name too (LocalDate, TextEnum, RichText); grep the package rather than guessing. A textEnum parameter is typed TextEnum (a string)domEvent) take the matching DOM type: POINTER → PointerEvent, KEYBOARD → KeyboardEvent, FOCUS → FocusEvent, CHANGE → Event, SUBMIT → SubmitEventasync and return a Promise<T> when the registration sets async: true. returns describes the resolved value’s type, not the Promisevoid; omit returns in the registrationEach key of the functions map is a function name and each value a Function object — see FUNCTION_LIBRARY_SPEC.md for its fields and PARAMETER_PATTERNS.md for parameter examples (optional, complex objects, arrays, textEnum, async, void, DOM events).
richText values