var keys = Object.keys || function(obj) {
obj = Object(obj)
var arr = []
for (var a in obj) arr.push(a)
return arr
}
var invert = function(obj) {
obj = Object(obj)
var result = {}
for (var a in obj) result[obj[a]] = a
return result
}
var entityMap = {
escape: {
'&': '&',
'<': '<',
'>': '>',
'"': '"',
"'": '''
}
}
entityMap.unescape = invert(entityMap.escape)
var entityReg = {
escape: RegExp('[' + keys(entityMap.escape).join('') + ']', 'g'),
unescape: RegExp('(' + keys(entityMap.unescape).join('|') + ')', 'g')
}

// 將HTML轉義為實體
function escape(html) {
if (typeof html !== 'string') return ''
return html.replace(entityReg.escape, function(match) {
return entityMap.escape[match]
})
}
// 將實體轉回為HTML
function unescape(str) {
if (typeof str !== 'string') return ''
return str.replace(entityReg.unescape, function(match) {
return entityMap.unescape[match]
})
}

// 將HTML轉義為實體
function escape(html){
var elem = document.createElement('div')
var txt = document.createTextNode(html)
elem.appendChild(txt)
return elem.innerHTML;
}
// 將實體轉回為HTML
function unescape(str) {
var elem = document.createElement('div')
elem.innerHTML = str
return elem.innerText || elem.textContent
}