JS Html转义和反转义（html编码和解码）的实现与使

var HtmlUtil = {
    /1.用浏览器内部转换器实现html编码（转义）/
    htmlEncode:function (html){
      //1.动态创建一个容器标签元素，如DIV
      var temp = document.createElement ("div");
      //2.然后将要转换的字符串设置为这个元素的innerText或者textContent
      (temp.textContent != undefined ) ? (temp.textContent = html) : (temp.innerText = html);
      //3.返回这个元素的innerHTML，即得到经过HTML编码转换的字符串了
      var output = temp.innerHTML;
      temp = null;
      return output;
    },
    /2.用浏览器内部转换器实现html解码（反转义）/
    htmlDecode:function (text){
      //1.动态创建一个容器标签元素，如DIV
      var temp = document.createElement("div");
      //2.然后将要转换的字符串设置为这个元素的innerHTML(ie，火狐，google都支持)
      temp.innerHTML = text;
      //3.返回这个元素的innerText或者textContent，即得到经过HTML解码的字符串了。
      var output = temp.innerText || temp.textContent;
      temp = null;
      return output;
    },
    /3.用正则表达式实现html编码（转义）/
    htmlEncodeByRegExp:function (str){ 
       var temp = "";
       if(str.length == 0) return "";
       temp = str.replace(/&/g,"&");
       temp = temp.replace(/</g,"&lt;");
       temp = temp.replace(/>/g,"&gt;");
       temp = temp.replace(/\s/g,"&nbsp;");
       temp = temp.replace(/\'/g,"&#39;");
       temp = temp.replace(/\"/g,"&quot;");
       return temp;
    },
    /4.用正则表达式实现html解码（反转义）/
    htmlDecodeByRegExp:function (str){ 
       var temp = "";
       if(str.length == 0) return "";
       temp = str.replace(/&amp;/g,"&");
       temp = temp.replace(/&lt;/g,"<");
       temp = temp.replace(/&gt;/g,">");
       temp = temp.replace(/&nbsp;/g," ");
       temp = temp.replace(/&#39;/g,"\'");
       temp = temp.replace(/&quot;/g,"\"");
       return temp; 
    },
    /5.用正则表达式实现html编码（转义）（另一种写法）/
    html2Escape:function(sHtml) {
       return sHtml.replace(/[<>&"]/g,function(c){return {'<':'&lt;','>':'&gt;','&':'&amp;','"':'&quot;'}[c];});
    },
    /6.用正则表达式实现html解码（反转义）（另一种写法）/
    escape2Html:function (str) {
       var arrEntities={'lt':'<','gt':'>','nbsp':' ','amp':'&','quot':'"'};
       return str.replace(/&(lt|gt|nbsp|amp|quot);/ig,function(all,t){return arrEntities[t];});
    }
  };

<div>&</div>
<div>&amp;</div>
<div id="testdiv"></div>
<div id="testdiv1"></div>
<div id="testdiv2"></div>

<div id="regdiv"></div>
<div id="regdiv1"></div>
<div id="regdiv2"></div>

<div id="regdiv3"></div>
<div id="regdiv4"></div>
<div id="regdiv5"></div>

var strHtml='<div style="color:blue">符号&amp;<div>';
  document.getElementById("testdiv").innerHTML=strHtml;

  var encodedHtml= HtmlUtil.htmlEncode(strHtml);// "&lt;div style="color:blue"&gt;符号&amp;amp;&lt;div&gt;"
  document.getElementById("testdiv1").innerHTML=encodedHtml;

  var decodedHtml=HtmlUtil.htmlDecode(encodedHtml);// '<div style="color:blue">符号&amp;<div>'
  document.getElementById("testdiv2").innerHTML=decodedHtml;

  var strHtml_1='<div style="color:red">符号&amp;<div>';
  document.getElementById("regdiv").innerHTML=strHtml_1;

  var encodedHtml_1 =HtmlUtil.htmlEncodeByRegExp(strHtml_1);// "&lt;div style="color:red"&gt;符号&amp;amp;&lt;div&gt;"
  document.getElementById("regdiv1").innerHTML=encodedHtml_1;

  var decodedHtml_1 =HtmlUtil.htmlDecodeByRegExp(encodedHtml_1);// '<div style="color:blue">符号&amp;<div>'
  document.getElementById("regdiv2").innerHTML=decodedHtml_1;

  var strHtml_2='<div style="color:green">符号&amp;<div>';
  document.getElementById("regdiv3").innerHTML=strHtml_2;

  var encodedHtml_2 =HtmlUtil.htmlEncodeByRegExp(strHtml_2);// "&lt;div style="color:green"&gt;符号&amp;amp;&lt;div&gt;"
  document.getElementById("regdiv4").innerHTML=encodedHtml_2;

  var decodedHtml_2 =HtmlUtil.htmlDecodeByRegExp(encodedHtml_2);// '<div style="color:green">符号&amp;<div>'
  document.getElementById("regdiv5").innerHTML=decodedHtml_2;

function removeHtmlTab(tab) {
return tab.replace(/<[^<>]+?>/g,'');//删除所有HTML标签
}
removeHtmlTab('<div id="test">zyl</div><span>zzc</span>');// zylzzc

function return2Br(str) {
  return str.replace(/\r?\n/g,"<br />");
}

function trimBr(str) {
  str=str.replace(/((\s| )\r?\n){3,}/g,"\r\n\r\n");//限制最多2次换行
  str=str.replace(/^((\s| )\r?\n)+/g,'');//清除开头换行
  str=str.replace(/((\s| )\r?\n)+$/g,'');//清除结尾换行
  return str;
}

function mergeSpace(str) {
  str=str.replace(/(\s| )+/g,' ');
  return str;
}