md018.js

// @ts-check

"use strict";

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

module.exports = {
  "names": [ "MD018", "no-missing-space-atx" ],
  "description": "No space after hash on atx style heading",
  "tags": [ "headings", "headers", "atx", "spaces" ],
  "function": function MD018(params, onError) {
    forEachLine(lineMetadata(), (line, lineIndex, inCode) => {
      if (!inCode &&
        /^#+[^# \t]/.test(line) &&
        !/#\s*$/.test(line) &&
        !line.startsWith("#️⃣")) {
        const hashCount = /^#+/.exec(line)[0].length;
        addErrorContext(
          onError,
          lineIndex + 1,
          line.trim(),
          null,
          null,
          [ 1, hashCount + 1 ],
          {
            "editColumn": hashCount + 1,
            "insertText": " "
          }
        );
      }
    });
  }
};