RT 将textarea 中的文本选中后 按下一个button 实现 替换效果~~~~~

js 实现 替换选中的文本

&lt;script&gt;<br>  function setCaret(){<br>   if(this.createTextRange){<br>    this.caretPos=document.selection.createRange().duplicate();<br>   }<br>  };<br><br>//保存当前光标位置,并且插入当前位置<br>  function insertAtCaret(textObj,textFeildValue){<br>   if(document.all){//ie<br>    if(textObj.createTextRange&amp;&amp;textObj.caretPos){<br>    var caretPos=textObj.caretPos;<br>    //alert(caretPos.text)<br>    caretPos.text=caretPos.text.charAt(caretPos.text.length-1)==''?textFeildValue+'':textFeildValue;<br>    caretPos.select();<br>    }else {<br>    textObj.value=textFeildValue;<br>    }<br>   }else {//ff<br>    if(textObj.setSelectionRange){<br>    var rangeStart=textObj.selectionStart;<br>    var rangeEnd=textObj.selectionEnd;<br>    var oldScrollTop = textObj.scrollTop;<br>    var oldScrollHeight = textObj.scrollHeight;<br>    var oldLen = textObj.value.length;<br>    var tempStr1=textObj.value.substring(0,rangeStart);<br>    var tempStr2=textObj.value.substring(rangeEnd);<br>    textObj.value=tempStr1+textFeildValue+tempStr2;<br>    textObj.selectionStart = textObj.selectionEnd = rangeStart + textFeildValue.length;<br>    if (textObj.value.length == oldLen) {<br>    textObj.scrollTop = textObj.scrollHeight;<br>    } else if (textObj.scrollHeight &gt; oldScrollHeight) {<br>    textObj.scrollTop = oldScrollTop + textObj.scrollHeight - oldScrollHeight;<br>    } else {<br>    textObj.scrollTop = oldScrollTop;<br>    }<br>    }else {<br>    alert(&quot;xxxxx&quot;);<br>    }<br>   }<br>  }<br>&lt;/script&gt;<br><br>&lt;textarea id=&quot;oTextArea&quot; onselect=&quot;setCaret()&quot; onclick=&quot;setCaret()&quot; onkeyup=&quot;setCaret()&quot;&gt;bbbbb&lt;/textarea&gt;&lt;input type=&quot;button&quot; onclick='insertAtCaret(document.getElementById(&quot;oTextArea&quot;),&quot;iii&quot;)' value=&quot;replace&quot;/&gt;