markdown-it/lib/rules_block/hr.js

// Horizontal rule

'use strict';


module.exports = function hr(state, startLine, endLine, silent) {
  var marker, cnt, ch, token,
      pos = state.bMarks[startLine] + state.tShift[startLine],
      max = state.eMarks[startLine];

  marker = state.src.charCodeAt(pos++);

  // Check hr marker
  if (marker !== 0x2A/* * */ &&
      marker !== 0x2D/* - */ &&
      marker !== 0x5F/* _ */) {
    return false;
  }

  // markers can be mixed with spaces, but there should be at least 3 one

  cnt = 1;
  while (pos < max) {
    ch = state.src.charCodeAt(pos++);
    if (ch !== marker && ch !== 0x20/* space */) { return false; }
    if (ch === marker) { cnt++; }
  }

  if (cnt < 3) { return false; }

  if (silent) { return true; }

  state.line = startLine + 1;

  token        = state.push('hr', 'hr', 0);
  token.map    = [ startLine, state.line ];
  token.markup = Array(cnt + 1).join(String.fromCharCode(marker));

  return true;
};