text: 'use strict'
  
  var entities = require('character-entities-html4')
  var legacy = require('character-entities-legacy')
  var hexadecimal = require('is-hexadecimal')
  var alphanumerical = require('is-alphanumerical')
  var dangerous = require('./dangerous.json')
  
  /* Expose. */
  module.exports = encode
  encode.escape = escape
  
  var own = {}.hasOwnProperty
  
  /* List of enforced escapes. */
  var escapes = ['"', "'", '<', '>', '&', '`']
  
  /* Map of characters to names. */
  var characters = construct()
  
  /* Default escapes. */
  var defaultEscapes = toExpression(escapes)
  
  /* Surrogate pairs. */
  var surrogatePair = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g
  
  /* Non-ASCII characters. */
  // eslint-disable-next-line no-control-regex, unicorn/no-hex-escape
  var bmp = /[\x01-\t\x0B\f\x0E-\x1F\x7F\x81\x8D\x8F\x90\x9D\xA0-\uFFFF]/g
  
  /* Encode special characters in `value`. */
  function encode(value, options) {
    var settings = options || {}
    var subset = settings.subset
    var set = subset ? toExpression(subset) : defaultEscapes
    var escapeOnly = settings.escapeOnly
    var omit = settings.omitOptionalSemicolons
  
    value = value.replace(set, function(char, pos, val) {
      return one(char, val.charAt(pos + 1), settings)
    })
  
    if (subset || escapeOnly) {
      return value
    }
  
    return value
      .replace(surrogatePair, replaceSurrogatePair)
      .replace(bmp, replaceBmp)
  
    function replaceSurrogatePair(pair, pos, val) {
      return toHexReference(
        (pair.charCodeAt(0) - 0xd800) * 0x400 +
          pair.charCodeAt(1) -
          0xdc00 +
          0x10000,
        val.charAt(pos + 2),
        omit
      )
    }
  
    function replaceBmp(char, pos, val) {
      return one(char, val.charAt(pos + 1), settings)
    }
  }
  
  /* Shortcut to escape special characters in HTML. */
  function escape(value) {
    return encode(value, {
      escapeOnly: true,
      useNamedReferences: true
    })
  }
  
  /* Encode `char` according to `options`. */
  function one(char, next, options) {
    var shortest = options.useShortestReferences
    var omit = options.omitOptionalSemicolons
    var named
    var numeric
  
    if ((shortest || options.useNamedReferences) && own.call(characters, char)) {
      named = toNamed(characters[char], next, omit, options.attribute)
    }
  
    if (shortest || !named) {
      numeric = toHexReference(char.charCodeAt(0), next, omit)
    }
  
    if (named && (!shortest || named.length < numeric.length)) {
      return named
    }
  
    return numeric
  }
  
  /* Transform `code` into an entity. */
  function toNamed(name, next, omit, attribute) {
    var value = '&' + name
  
    if (
      omit &&
      own.call(legacy, name) &&
      dangerous.indexOf(name) === -1 &&
      (!attribute || (next && next !== '=' && !alphanumerical(next)))
    ) {
      return value
    }
  
    return value + ';'
  }
  
  /* Transform `code` into a hexadecimal character reference. */
  function toHexReference(code, next, omit) {
    var value = '&#x' + code.toString(16).toUpperCase()
    return omit && next && !hexadecimal(next) ? value : value + ';'
  }
  
  /* Create an expression for `characters`. */
  function toExpression(characters) {
    return new RegExp('[' + characters.join('') + ']', 'g')
  }
  
  /* Construct the map. */
  function construct() {
    var chars = {}
    var name
  
    for (name in entities) {
      chars[entities[name]] = name
    }
  
    return chars
  }
  