原作者的答案在这里。

这是我最喜欢的解码HTML字符的方法。使用此代码的优点是还保留了标记。

function decodeHtml(html) {
    var txt = document.createElement("textarea");
    txt.innerHTML = html;
    return txt.value;
}

例如:http://jsfiddle.net/k65s3/

输入:

Entity:&nbsp;Bad attempt at XSS:<script>alert('new\nline?')</script><br>

输出:

Entity: Bad attempt at XSS:<script>alert('new\nline?')</script><br>

我不建议使用jQuery代码作为答案。虽然它不会将要解码的字符串插入到页面中，但它确实会创建脚本和HTML元素等内容。这代码比我们需要的多。相反，我建议使用更安全、更优化的函数。

var decodeEntities = (function() {
  // this prevents any overhead from creating the object each time
  var element = document.createElement('div');

  function decodeHTMLEntities (str) {
    if(str && typeof str === 'string') {
      // strip script/html tags
      str = str.replace(/<script[^>]*>([\S\s]*?)<\/script>/gmi, '');
      str = str.replace(/<\/?\w(?:[^"'>]|"[^"]*"|'[^']*')*>/gmi, '');
      element.innerHTML = str;
      str = element.textContent;
      element.textContent = '';
    }

    return str;
  }

  return decodeHTMLEntities;
})();

http://jsfiddle.net/LYteC/4/

要使用这个函数，只需调用decodeEntities(“&”)，它将使用与jQuery版本相同的底层技术——但是没有jQuery的开销，并且在清除输入中的HTML标记之后。请参阅Mike Samuel关于如何过滤HTML标记的公认答案的评论。

这个函数可以很容易地作为jQuery插件使用，只需在您的项目中添加以下行即可。

jQuery.decodeEntities = decodeEntities;

以下是完整版本

function htmldecode(s){
    window.HTML_ESC_MAP = {
    "nbsp":" ","iexcl":"¡","cent":"¢","pound":"£","curren":"¤","yen":"¥","brvbar":"¦","sect":"§","uml":"¨","copy":"©","ordf":"ª","laquo":"«","not":"¬","reg":"®","macr":"¯","deg":"°","plusmn":"±","sup2":"²","sup3":"³","acute":"´","micro":"µ","para":"¶","middot":"·","cedil":"¸","sup1":"¹","ordm":"º","raquo":"»","frac14":"¼","frac12":"½","frac34":"¾","iquest":"¿","Agrave":"À","Aacute":"Á","Acirc":"Â","Atilde":"Ã","Auml":"Ä","Aring":"Å","AElig":"Æ","Ccedil":"Ç","Egrave":"È","Eacute":"É","Ecirc":"Ê","Euml":"Ë","Igrave":"Ì","Iacute":"Í","Icirc":"Î","Iuml":"Ï","ETH":"Ð","Ntilde":"Ñ","Ograve":"Ò","Oacute":"Ó","Ocirc":"Ô","Otilde":"Õ","Ouml":"Ö","times":"×","Oslash":"Ø","Ugrave":"Ù","Uacute":"Ú","Ucirc":"Û","Uuml":"Ü","Yacute":"Ý","THORN":"Þ","szlig":"ß","agrave":"à","aacute":"á","acirc":"â","atilde":"ã","auml":"ä","aring":"å","aelig":"æ","ccedil":"ç","egrave":"è","eacute":"é","ecirc":"ê","euml":"ë","igrave":"ì","iacute":"í","icirc":"î","iuml":"ï","eth":"ð","ntilde":"ñ","ograve":"ò","oacute":"ó","ocirc":"ô","otilde":"õ","ouml":"ö","divide":"÷","oslash":"ø","ugrave":"ù","uacute":"ú","ucirc":"û","uuml":"ü","yacute":"ý","thorn":"þ","yuml":"ÿ","fnof":"ƒ","Alpha":"Α","Beta":"Β","Gamma":"Γ","Delta":"Δ","Epsilon":"Ε","Zeta":"Ζ","Eta":"Η","Theta":"Θ","Iota":"Ι","Kappa":"Κ","Lambda":"Λ","Mu":"Μ","Nu":"Ν","Xi":"Ξ","Omicron":"Ο","Pi":"Π","Rho":"Ρ","Sigma":"Σ","Tau":"Τ","Upsilon":"Υ","Phi":"Φ","Chi":"Χ","Psi":"Ψ","Omega":"Ω","alpha":"α","beta":"β","gamma":"γ","delta":"δ","epsilon":"ε","zeta":"ζ","eta":"η","theta":"θ","iota":"ι","kappa":"κ","lambda":"λ","mu":"μ","nu":"ν","xi":"ξ","omicron":"ο","pi":"π","rho":"ρ","sigmaf":"ς","sigma":"σ","tau":"τ","upsilon":"υ","phi":"φ","chi":"χ","psi":"ψ","omega":"ω","thetasym":"ϑ","upsih":"ϒ","piv":"ϖ","bull":"•","hellip":"…","prime":"′","Prime":"″","oline":"‾","frasl":"⁄","weierp":"℘","image":"ℑ","real":"ℜ","trade":"™","alefsym":"ℵ","larr":"←","uarr":"↑","rarr":"→","darr":"↓","harr":"↔","crarr":"↵","lArr":"⇐","uArr":"⇑","rArr":"⇒","dArr":"⇓","hArr":"⇔","forall":"∀","part":"∂","exist":"∃","empty":"∅","nabla":"∇","isin":"∈","notin":"∉","ni":"∋","prod":"∏","sum":"∑","minus":"−","lowast":"∗","radic":"√","prop":"∝","infin":"∞","ang":"∠","and":"∧","or":"∨","cap":"∩","cup":"∪","int":"∫","there4":"∴","sim":"∼","cong":"≅","asymp":"≈","ne":"≠","equiv":"≡","le":"≤","ge":"≥","sub":"⊂","sup":"⊃","nsub":"⊄","sube":"⊆","supe":"⊇","oplus":"⊕","otimes":"⊗","perp":"⊥","sdot":"⋅","lceil":"⌈","rceil":"⌉","lfloor":"⌊","rfloor":"⌋","lang":"〈","rang":"〉","loz":"◊","spades":"♠","clubs":"♣","hearts":"♥","diams":"♦","\"":"quot","amp":"&","lt":"<","gt":">","OElig":"Œ","oelig":"œ","Scaron":"Š","scaron":"š","Yuml":"Ÿ","circ":"ˆ","tilde":"˜","ndash":"–","mdash":"—","lsquo":"‘","rsquo":"’","sbquo":"‚","ldquo":"“","rdquo":"”","bdquo":"„","dagger":"†","Dagger":"‡","permil":"‰","lsaquo":"‹","rsaquo":"›","euro":"€"};
    if(!window.HTML_ESC_MAP_EXP)
        window.HTML_ESC_MAP_EXP = new RegExp("&("+Object.keys(HTML_ESC_MAP).join("|")+");","g");
    return s?s.replace(window.HTML_ESC_MAP_EXP,function(x){
        return HTML_ESC_MAP[x.substring(1,x.length-1)]||x;
    }):s;
}

使用

htmldecode("∑ >€");

向页面中注入不受信任的HTML是危险的，如如何使用jQuery解码HTML实体中所述。

一种替代方法是使用PHP html_entity_decode的纯javascript实现(来自http://phpjs.org/functions/html_entity_decode:424)。这个例子应该是这样的:

var varTitle = html_entity_decode("Chris' corner");

这里有一个不需要创建div的快速方法，并解码“最常见的”HTML转义字符:

function decodeHTMLEntities(text) {
    var entities = [
        ['amp', '&'],
        ['apos', '\''],
        ['#x27', '\''],
        ['#x2F', '/'],
        ['#39', '\''],
        ['#47', '/'],
        ['lt', '<'],
        ['gt', '>'],
        ['nbsp', ' '],
        ['quot', '"']
    ];

    for (var i = 0, max = entities.length; i < max; ++i) 
        text = text.replace(new RegExp('&'+entities[i][0]+';', 'g'), entities[i][1]);

    return text;
}

受Robert K的解决方案的启发，这个版本不剥离HTML标记，而且同样安全。

var decode_entities = (function() {
    // Remove HTML Entities
    var element = document.createElement('div');

    function decode_HTML_entities (str) {

        if(str && typeof str === 'string') {

            // Escape HTML before decoding for HTML Entities
            str = escape(str).replace(/%26/g,'&').replace(/%23/g,'#').replace(/%3B/g,';');

            element.innerHTML = str;
            if(element.innerText){
                str = element.innerText;
                element.innerText = '';
            }else{
                // Firefox support
                str = element.textContent;
                element.textContent = '';
            }
        }
        return unescape(str);
    }
    return decode_HTML_entities;
})();