markdown-it/lib/rules_inline/entity.js

// Proceess html entity - {, ¯, ", ...

'use strict';

var entities          = require('../common/entities');
var escapeHtml        = require('../helpers').escapeHtml;
var isValidEntityCode = require('../helpers').isValidEntityCode;
var fromCodePoint     = require('../helpers').fromCodePoint;


var DIGITAL_RE = /^&#((?:x[a-f0-9]{1,8}|[0-9]{1,8}));/i;
var NAMED_RE   = /^&([a-z][a-z0-9]{1,31});/i;


module.exports = function entity(state) {
  var ch, code, match, pos = state.pos, max = state.posMax;

  if (state.src.charCodeAt(pos) !== 0x26/* & */) { return false; }

  if (pos + 1 < max) {
    ch = state.src.charCodeAt(pos + 1);

    if (ch === 0x23 /* # */) {
      match = state.src.slice(pos).match(DIGITAL_RE);
      if (match) {
        code = match[1][0].toLowerCase() === 'x' ? parseInt(match[1].slice(1), 16) : parseInt(match[1], 10);
        state.pending += isValidEntityCode(code) ? escapeHtml(fromCodePoint(code)) : fromCodePoint(0xFFFD);
        state.pos += match[0].length;
        return true;
      }
    } else {
      match = state.src.slice(pos).match(NAMED_RE);
      if (match) {
        if (entities.hasOwnProperty(match[1])) {
          state.pending += escapeHtml(entities[match[1]]);
          state.pos += match[0].length;
          return true;
        }
      }
    }
  }

  state.pending += '&amp;';
  state.pos++;
  return true;
};