map

frontmatter.js

"use strict";

const matter = [
  null,
  null,
  null,
  {
    title: "Advanced title",
    description: "Some advance story",
    date: "2023-01-22T23:51:45.574Z",
  },
  {
    title: "Another page",
    description: "Page description",
  },
  null,
];

//filter array where matter is not null
const filteredMatter = matter.filter((item) => item !== null);

const pageMap = [
  {
    kind: "Meta",
    data: {
      index: "Introduction",
      another: "Another Page",
      advanced: "Advanced (A Folder)",
      about: {
        title: "About",
        type: "page",
      },
      contact: {
        title: "Contact ↗",
        type: "page",
        href: "https://twitter.com/shuding_",
        newWindow: true,
      },
    },
  },
  {
    kind: "MdxPage",
    name: "about",
    route: "/about",
  },
  {
    kind: "Folder",
    name: "advanced",
    route: "/advanced",
    children: [
      {
        kind: "MdxPage",
        name: "satori",
        route: "/advanced/satori",
      },
    ],
  },
  {
    kind: "MdxPage",
    name: "advanced",
    route: "/advanced",
    frontMatter: {
      title: "Advanced title",
      description: "Some advance story",
      date: "2023-01-22T23:51:45.574Z",
    },
  },
  {
    kind: "MdxPage",
    name: "another",
    route: "/another",
    frontMatter: {
      title: "Another page",
      description: "Page description",
    },
  },
  {
    kind: "MdxPage",
    name: "index",
    route: "/",
    frontMatter: {
      title: "Introduction",
      description:
        "A simple, powerful and flexible site generation framework with everything you love from Next.js.",
    },
  },
];

// get from pageMap where kind is MdxPage
const mdxPages = pageMap.filter((item) => item.kind === "MdxPage");
// get from mdxPages where frontMatter is not null
const mdxPagesWithFrontMatter = mdxPages.filter(
    (item) => item.frontMatter !== undefined
);

// get frontMatter from pageMap where kind is MdxPage
const mdxPagesFrontMatter = pageMap.filter(
  (item) => item.kind === "MdxPage" && item.frontMatter !== undefined
);