文本编辑器代码如何写

【实例名称】

文本编辑器

【实例描述】

 在网站提供的邮箱中，经常会使用文本编辑器，以实现文本内容的层次感和美观性。本例将制作一个简单的文本编辑器，主要学习实现文本编辑器的原理。

【实例代码】

    <script language="javascript">
var edit;       //当前选择的文本编辑区域对象
var RangeType;  //对象类别
function start() //开始初始化编辑器-编辑区域是Iframe
{
 Editor.document.designMode="ON";
 Editor.document.open();
 Editor.document.write(myTextArea.value);
 Editor.document.close();
    fnInit()
}
function setFocus() {
   Editor.focus();  //编辑器或去焦点
}
function selectRange(){
 edit = Editor.document.selection.createRange();  //编辑器的文本选择区域
 RangeType = Editor.document.selection.type;
}
//包装文本选定区域的执行命令
function execCommand(command,para) { 
  setFocus();
        selectRange(); 
    if (para=="")   //没有参数的情况
        edit.execCommand(command)
    else
    edit.execCommand(command, false, arguments[1]);
  Editor.focus();
  if (RangeType != "Control") edit.select();
}
//获取或设置文本的格式-字体、字号
function doSelectC(str,el) {
   var Index = el.selectedIndex;
  if (Index != 0)
  { el.selectedIndex = 0;
  execCommand(str,el.options[Index].text);
    }
}
//获取或设置当前选定块的格式化标签
function doSelectCl(str,el) 
{
   var Index = el.selectedIndex;
  if (Index != 0)
  { el.selectedIndex = 0;
  execCommand(str,"<"+el.options[Index].value+">");
  }
}
//初始化
function fnInit(){
      for (i=0; i<document.all.length; i++)
            document.all(i).unselectable = "off";  //指定不选中任何元素
      getSystemFonts();
}
//获取系统字体的方法
function getSystemFonts()
{  
var a=dlgHelper.fonts.count;
var fArray = new Array();
var oOption = document.createElement("OPTION");
oOption.text = "字体";
oOption.value = "0";
selectFontName.add(oOption);
//使用DOM方法createElement将字体依次添加到复选列表中
for (i = 1;i < dlgHelper.fonts.count;i++)
 { 
  fArray[i] = dlgHelper.fonts(i);
  var oOption = document.createElement("OPTION");
  oOption.text = fArray[i];
  oOption.Value = i;
  selectFontName.add(oOption); 
 } 
}
//格式化，保全script、textarea、xmp、pre和style内容
function formatfor(va) {
  var t=va.replace(/\r/g,'');
  t = t.replace(/(<(script|textarea|xmp|pre|style).*?>)([^\r]*?)(<\/\2>)/img,
function (){return arguments[1]+arguments[3].replace(/\n/g, "\r")+arguments[4]})
  t = t.replace(/\n/g, "");
  return t
}
function fontsize(el) //改变字体的方法
{var Index=el.selectedIndex
var addpre="<font size="+el.options[Index].value+">"
if(Index>7)addpre="<font style='font-size:"+el.options[Index].value+"pt'>"
var oSel = Editor.document.selection.createRange()
var sBookmark = oSel.getBookmark()
var oSelhtml=oSel.htmlText
if(oSelhtml!="")
{
//定位选中内容
var conts=oSelhtml
var textLength = Editor.document.body.innerText.length
oSel.moveStart("character", -1*textLength)
var contp=formatfor(oSel.htmlText)
var conta=formatfor(Editor.document.body.innerHTML)
var contpa=''
var partC=""
var partB=""
var partA=""
var m=0
m=conta.indexOf(contp.substr(0,3))
var f=contp.length
for(;f>0;f--)
{if(conta.substr(m,f)==contp.substr(0, f)){contpa=contp.substr(0,f);partC=conta.substr(m+f);break}}
var ko=contp.substr(f)
var kol=ko.length
var ty=conta.substr(m+f,kol)
var hu=""
for(var b=1;b<kol;b++)if(ko.substr(b)==ty.substr(0,kol-b)){hu=ko.substr(b);contpa+=hu;partC=partC.substr(kol-b);break}
var k=contpa.length
cont=conts.replace(/\n/g, "")
var u=cont.length
if(cont==contpa.substr(k-u)){partB=cont;partA=contpa.substr(0,k-u)}else{
for(u=cont.length;u>0;u--)
{if(cont.lastIndexOf(contpa.substr(k-u))!=-1){partB0=contpa.substr(k-u);partA0=contpa.substr(0,k-u);break}}
contt=formatfor(conts)
if(hu!="")if(contt.substr(contt.length-kol)==ko)contt=contt.substr(0,contt.length-kol)+hu
u=contt.length
var youm=contpa.lastIndexOf(contt)
if(youm!=-1){partB=contt;partA=contpa.substr(0,youm);partC=contpa.substr(youm+u)+partC}else{
for(;u>0;u--){if(contt.lastIndexOf(contpa.substr(k-u))!=-1){partB1=contpa.substr(k-u);partA1=contpa.substr(0,k-u);break}}
if(partB1.length>partB0.length){partB=partB1;partA=partA1}else{partB=partB0;partA=partA0}
 }
}
if(partB.substr(partB.length-1)=="<"){partB=partB.substr(0,partB.length-1);partC="<"+partC}
if(partB.substr(partB.length-2)=="</"){partB=partB.substr(0,partB.length-2);partC="</"+partC}
//保护textarea、xmp、script和style的内容不被改变
var cook=[]
partA=partA.replace(/(<(script|textarea|xmp|style).*?>)[\s\S]*?<\/\2>/ig,
function (){co=cook.length
cook[co]=arguments[0];return "<cook"+co+">"})
var ook=""
partA=partA.replace(/(<(script|textarea|xmp|style).*?>)[\s\S]*?$/i,
function (){co=cook.length
ook=arguments[2]
cook[co]=arguments[0];return "<cook"+co+">"})
if(ook!=""){fd="(^[\\s\\S]*?<\/"+ook+">)"
jk=new RegExp(fd,["i"])
if(jk.test(partB)){jk.exec(partB)
co=cook.length
cook[co]=RegExp.$1
partB=partB.replace(jk,"<cook"+co+">")}}
partB=partB.replace(/(<(script|textarea|xmp|style).*?>)[\s\S]*?<\/\2>/ig,
function (){co=cook.length
cook[co]=arguments[0];return "<cook"+co+">"})
ook=""
partB=partB.replace(/(<(script|textarea|xmp|style).*?>)[\s\S]*?$/i,
function (){co=cook.length
ook=arguments[2]
cook[co]=arguments[0];return "<cook"+co+">"})
if(ook!=""){fd="(^[\\s\\S]*?<\/"+ook+">)"
jk=new RegExp(fd,["i"])
if(jk.test(partC)){jk.exec(partC)
co=cook.length
cook[co]=RegExp.$1
partC=partC.replace(jk,"<cook"+co+">")}}
partC=partC.replace(/(<(script|textarea|xmp|style).*?>)[\s\S]*?<\/\2>/ig,
function (){co=cook.length
cook[co]=arguments[0];return "<cook"+co+">"})
//处理字体
var dol=[]
var dos=[]
var lon=[]
fd="<FONT([^>]*?)>"
jk=new RegExp(fd,["im"])
while(jk.test(partB)){ce=dol.length
jk.exec(partB)
dol[ce]=RegExp.$1
partB=partB.replace(jk,"<site"+ce+">")
}
ce=dol.length-1
for(;ce>-1;ce--)
{kjc="<site"+ce+">"
fd=kjc+'(.*?)<\/font>'
jk=new RegExp(fd,["im"])
if(jk.test(partB)){dos[dos.length]=ce
jk.exec(partB)
ko3=kjc+RegExp.$1+"</site"+ce+">"
partB=partB.replace(jk,ko3)
}else{lon[lon.length]=ce}
}
partB=partB.replace(/<\/font>/img,"<lonf>")
for(var c=dos.length-1;c>-1;c--)
{
uts=dol[dos[c]]
if(""==(uts.replace(/size=[0-7+]+/i,"").replace(/style=("|')FONT-SIZE: [0-9.]+.*;*("|')/im,"").replace(/[\s\n\r]+/mg,""))){partB=partB.replace("<site"+dos[c]+">","")
partB=partB.replace("</site"+dos[c]+">","")}else{partB=partB.replace("<site"+dos[c]+">","<font"+uts.replace(/ size=[0-7+]+/im,"").replace(/FONT-SIZE: [0-9.]+pt/im,"").replace(/ style=("|');*("|')/im,"")+">")
partB=partB.replace("</site"+dos[c]+">","</font>")}
}
//处理其他标签
var addend=""
var mio=[]
partB=partB.replace(/<([^<> ]*?) [^<>]*?style=[^<>]*?FONT-SIZE: [0-9.]+[^<>]*?>/img,
function (){notv="|select|input|option|object|"
if(notv.indexOf("|"+arguments[1].toLowerCase()+"|")==-1){
op=mio.length
mio[op]=arguments[0]
return "<opis"+op+">"}else{return arguments[0]}})
kba=["h1","h2","h3","h4","h5","h6","pre","button","listing","big","small","tt","code","kbd","samp","td","\/td","caption","\/caption","th","\/th","tr","\/tr","table","\/table","thead","\/thead","tbody","\/tbody","tfoot","\/tfoot"]
for(b in kba){
fd="<("+kba[b]+")[^<>]*?>"
jk=new RegExp(fd,["img"])
partB=partB.replace(jk,
function (){op=mio.length
mio[op]=arguments[0]
return "<opis"+op+">"})
}
//收尾工作
liming=[]
partB=partB.replace(/<(opis|site|lonf)([0-9]*)>/g,
function(){var op=liming.length
if(arguments[1]=="opis"){liming[op]=mio[parseInt(arguments[2])]}
if(arguments[1]=="site"){liming[op]="<font"+dol[parseInt(arguments[2])]+">"}
if(arguments[1]=="lonf"){liming[op]="</font>"}
return "<duan"+op+">"
})
if(liming.length>0){
partB=partB.replace(/^(.+?)(<duan0>)/m,function(){if(""!=arguments[1]){return addpre+arguments[1]+"</font>"+arguments[2]}
else{return arguments[0]}})
var op=liming.length-1
for(var kc=0;kc<op;kc++){
fd="(<duan"+kc+">)(.+?)(<duan"+(kc+1)+">)"
jk=new RegExp(fd,["m"])
partB=partB.replace(jk,
function(){if(""!=arguments[2]){return arguments[1]+addpre+arguments[2]+"</font>"+arguments[3]}
else{return arguments[0]}})}
fd="(<duan"+op+">)(.+?)$"
jk=new RegExp(fd,["m"])
partB=partB.replace(jk,function(){if(""!=arguments[2]){return arguments[1]+addpre+arguments[2]+"</font>"}
else{return arguments[0]}})
}
else{partB=addpre+partB+"</font>"
}
partB=partB.replace(/<duan([0-9]+)>/g,function(){return liming[parseInt(arguments[1])]})
var endtemp=partA+partB+partC
for(vof in cook)endtemp=endtemp.replace("<cook"+vof+">",cook[vof])
Editor.document.body.innerHTML=endtemp
var vrvd=Editor.document.selection.createRange()
vrvd.moveToBookmark(sBookmark)
vrvd.select()
}
else{
Editor.document.selection.createRange().pasteHTML(addpre+"</font>")
}Editor.focus()
el.blur()
el.selectedIndex=0}
</script>
 

【运行效果】

【难点剖析】

本例的重点是字体的获取，以及执行命令“execCommand”。字体获取使用的是方法getSystemFonts”，方法中的“dlgHelpel"”对象必须在页面中注册，本例中注册的代码是“OBJECT id=dlgHelper CLASSID=“clsid：3050P819-98b5-11cf-bb82—00aa00bdceob”width=“Opx”height=“0px”><／OBJECT>”。ExecCommand是文本编辑器中的一个重要方法，主要用于样式的变更。

【源码下载】

本实例JS代码下载