remark-flexible-toc/dist/index.js

Remark plugin to expose the table of contents via Vfile.data or via an option reference

import { visit, CONTINUE } from "unist-util-visit";
import GithubSlugger from "github-slugger";
import { toString } from "mdast-util-to-string";
const DEFAULT_SETTINGS = {
    tocName: "toc",
    tocRef: [],
    maxDepth: 6,
    skipLevels: [1],
    skipParents: [],
};
/**
 * adds numberings to the TOC items.
 * why "number[]"? It is because up to you joining with dot or dash or slicing the first number (reserved for h1)
 *
 * [1]
 * [1,1]
 * [1,2]
 * [1,2,1]
 */
function addNumbering(arr) {
    for (let i = 0; i < arr.length; i++) {
        const tocItem = arr[i];
        const depth = tocItem.depth;
        let numbering;
        const prevObj = i > 0 ? arr[i - 1] : undefined;
        const prevDepth = prevObj ? prevObj.depth : undefined;
        const prevNumbering = prevObj ? prevObj.numbering : undefined;
        if (!prevNumbering || !prevDepth) {
            numbering = Array.from({ length: depth }, () => 1);
        }
        else if (depth === prevDepth) {
            numbering = [...prevNumbering];
            numbering[depth - 1]++;
        }
        else if (depth > prevDepth) {
            numbering = [
                ...prevNumbering,
                ...Array.from({ length: depth - prevDepth }, // if depth is more bigger than prevDepth, put more "1" inside the array
                () => 1),
            ];
        }
        else {
            // if (depth < prevDepth)
            numbering = prevNumbering.slice(0, depth);
            numbering[depth - 1]++;
        }
        tocItem.numbering = numbering;
    }
}
const RemarkFlexibleToc = (options) => {
    const settings = Object.assign({}, DEFAULT_SETTINGS, options);
    const exludeRegexFilter = settings.exclude &&
        (Array.isArray(settings.exclude)
            ? new RegExp("^(" + settings.exclude.join("|") + ")$", "i")
            : new RegExp("^(" + settings.exclude + ")$", "i"));
    return (tree, file) => {
        const slugger = new GithubSlugger();
        const tocItems = [];
        visit(tree, "heading", (_node, _index, _parent) => {
            /* v8 ignore next -- @preserve */
            if (!_parent || typeof _index === "undefined")
                return;
            const depth = _node.depth;
            const value = toString(_node, { includeImageAlt: false });
            let href = `#${settings.prefix ?? ""}${slugger.slug(value)}`;
            const parent = _parent.type;
            // maxDepth check
            if (depth > settings.maxDepth)
                return CONTINUE;
            // skipLevels check
            if (settings.skipLevels.includes(depth))
                return CONTINUE;
            // skipParents check
            if (parent !== "root" && settings.skipParents.includes(parent))
                return CONTINUE;
            // exclude check
            if (exludeRegexFilter && exludeRegexFilter.test(value))
                return CONTINUE;
            // Other remark plugins can store custom data in node.data.hProperties
            // I omitted node.data.hName and node.data.hChildren since not related with toc
            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
            // @ts-ignore, vscode resolves the type but tsc build raises an error awkwardly, saying "hProperties" does not exist in "HeadingData".
            const hProperties = _node.data?.hProperties;
            const data = hProperties ? { ...hProperties } : undefined;
            if (data?.["id"])
                href = `#${data["id"]}`;
            tocItems.push({
                value,
                href,
                depth,
                numbering: [],
                parent,
                ...(data && { data }),
            });
            return CONTINUE;
        });
        addNumbering(tocItems);
        // it is allowed to modify the TOC in the callback
        settings.callback?.(tocItems);
        // method - 1 for exposing the data via vfile.data **************************
        // other plugins are not allowed to mutate the exposed TOC
        // The spreading is slower than push but need to fresh copy
        file.data[settings.tocName] = [...tocItems];
        // method - 2 for exposing the data via reference array *********************
        if (options?.tocRef) {
            // prevent dublication if the plugin is called more than once
            settings.tocRef.length = 0;
            tocItems.forEach((tocItem) => {
                // the tocRef is not allowed to mutate the vfile.data.toc
                settings.tocRef.push(tocItem);
            });
        }
    };
};
export default RemarkFlexibleToc;
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