riot/compiler

import entities from './entities.json' assert { type: 'json' }

const HTMLEntityRe = /&(\S+);/g
const HEX_NUMBER = /^[\da-fA-F]+$/
const DECIMAL_NUMBER = /^\d+$/

/**
 * Encode unicode hex html entities like for example Ȣ
 * @param   {string} string - input string
 * @returns {string} encoded string
 */
export function encodeHex(string) {
  const hex = string.substr(2)

  return HEX_NUMBER.test(hex) ? String.fromCodePoint(parseInt(hex, 16)) : string
}

/**
 * Encode unicode decimal html entities like for example Þ
 * @param   {string} string - input string
 * @returns {string} encoded string
 */
export function encodeDecimal(string) {
  const nr = string.substr(1)

  return DECIMAL_NUMBER.test(nr)
    ? String.fromCodePoint(parseInt(nr, 10))
    : string
}

/**
 * Encode html entities in strings like  
 * @param   {string} string - input string
 * @returns {string} encoded string
 */
export default function encodeHTMLEntities(string) {
  return string.replace(HTMLEntityRe, (match, entity) => {
    const [firstChar, secondChar] = entity

    if (firstChar === '#') {
      return secondChar === 'x' ? encodeHex(entity) : encodeDecimal(entity)
    } else {
      return entities[entity] || entity
    }
  })
}