function StoreCaret(textEl){
if(textEl.createTextRange){
textEl.caretPos=document.selection.createRange().duplicate();
}
}
function InsertAtCaret(textEl,text){
if(textEl.createTextRange && textEl.caretPos){
var caretPos=textEl.caretPos;
caretPos.text=caretPos.text.charAt(caretPos.text.length-1)==' '?text+' ':text;
}else{
textEl.value=text;
}
}
function DeleteAtCaret(textEl,fileEl){
textEl.value=textEl.value.replace(fileEl.value,"");
}

//使用方法：