md020.js

// @ts-check

"use strict";

const { addErrorContext, forEachLine } = require("../helpers");
const { lineMetadata } = require("./cache");

module.exports = {
  "names": [ "MD020", "no-missing-space-closed-atx" ],
  "description": "No space inside hashes on closed atx style heading",
  "tags": [ "headings", "headers", "atx_closed", "spaces" ],
  "function": function MD020(params, onError) {
    forEachLine(lineMetadata(), (line, lineIndex, inCode) => {
      if (!inCode) {
        const match =
          /^(#+)([ \t]*)([^#]*?[^#\\])([ \t]*)((?:\\#)?)(#+)(\s*)$/.exec(line);
        if (match) {
          const [
            ,
            leftHash,
            { "length": leftSpaceLength },
            content,
            { "length": rightSpaceLength },
            rightEscape,
            rightHash,
            { "length": trailSpaceLength }
          ] = match;
          const leftHashLength = leftHash.length;
          const rightHashLength = rightHash.length;
          const left = !leftSpaceLength;
          const right = !rightSpaceLength || rightEscape;
          const rightEscapeReplacement = rightEscape ? `${rightEscape} ` : "";
          if (left || right) {
            const range = left ?
              [
                1,
                leftHashLength + 1
              ] :
              [
                line.length - trailSpaceLength - rightHashLength,
                rightHashLength + 1
              ];
            addErrorContext(
              onError,
              lineIndex + 1,
              line.trim(),
              left,
              right,
              range,
              {
                "editColumn": 1,
                "deleteCount": line.length,
                "insertText":
                  `${leftHash} ${content} ${rightEscapeReplacement}${rightHash}`
              }
            );
          }
        }
      }
    });
  }
};