Convert non-safe chars into HTML entities (JS)

escape.js

/**
 * Converts non-safe chars into HTML entities.
 * @author amekusa
 */
function escape(str) {
  if (!str) return '';
  let map = {
    '&': 'amp',
    '"': 'quot',
    "'": 'apos',
    '<': 'lt',
    '>': 'gt'
  };
  let ents = Object.values(map).join('|'); // to avoid double-escape '&'s
  let find = new RegExp(`["'<>]|(&(?!${ents};))`, 'g'); // regex negative match = (?!word)
  return `${str}`.replace(find, found => `&${map[found]};`);
}

This also avoids doubly escaping &s.