Veta Veta

JavaScript API

Veta uses JavaScript for three kinds of project files:

data/*.js       -> global data producers
pages/*.js      -> page generators
filters/*.js    -> template filters
functions/*.js  -> template functions

JavaScript files are self-contained and synchronous. They do not use imports, module loading, or asynchronous promises. Each file must export one default function.

Runtime Context

The default export receives a context object as its first argument.

Common context keys:

files
httpClient
parse
env

Additional context keys depend on where the file runs.

data/*.js

Data files run while global data is being loaded, so they do not receive data.

export default function({ env, files, httpClient }) {
  return {
    mode: env.VETA_MODE || "production",
  };
}

Return any JSON-compatible value. The value becomes part of data using the file path as its key.

Example:

data/github.js -> data.github

pages/*.js

Page generators receive loaded global data:

export default function({ data, parse }) {
  const { html } = parse.markdown("# Home");

  return [
    {
      permalink: "/",
      template: "base",
      title: data.site.name,
      content: html,
    },
  ];
}

Return an array of page objects. Templated content is passed unchanged and trusted to its template, while template-less content is written unchanged as raw output. Use parse.markdown(text) and parse.renderComponents(text) explicitly when a generator needs those transformations.

filters/*.js

Filters receive the runtime context, the input value, and one optional parameter:

export default function({ data }, input, parameter) {
  const prefix = parameter || data.site.name;
  return `${prefix}: ${input}`;
}

functions/*.js

Template functions receive the runtime context followed by explicit template arguments:

export default function({ page, data, files, parse }, value, length) {
  return String(value || page.title).slice(0, Number(length));
}

Use the file stem as a function in Pongo templates and components:

{{ excerpt(page.content, 120) }}

Use it in a template:

{{ page.title|prefix:"Post" }}

No Global Veta

Veta does not expose runtime APIs through a global Veta object. Always use the context argument:

export default function({ files }) {
  return files.listFiles("content/**/*.md");
}

Console

The console object is available as a JavaScript global:

export default function() {
  console.log("Generating pages");
  return [];
}

Supported methods are debug, error, info, log, and warn.

Execution Model

Veta executes JavaScript synchronously. Promise-like return values are rejected.

Use synchronous calls only:

export default function({ httpClient, parse }) {
  const response = httpClient.get("https://example.com/data.json");
  return parse.json(response.body);
}

Do not return a Promise:

export default async function() {
  return [];
}

API Pages