JS實現HTML實體與字符的相互轉換

function stringToEntity(str,radix){
  let arr=str.split('')
  radix=radix||0
  let tmp=arr.map(item=>
`&#${(radix?'x'+item.charCodeAt(0).toString(16):item.charCodeAt(0))};`).join('')
  console.log(`'${str}' 轉實體為 '${tmp}'`)
  return tmp
}
function entityToString(entity){
  let entities=entity.split(';')
  entities.pop()
  let tmp=entities.map(item=>String.fromCharCode(
  item[2]==='x'?parseInt(item.slice(3),16):parseInt(item.slice(2)))).join('')
  console.log(`'${entity}' 轉字符串為 '${tmp}'`)
  return tmp
}