原生javascript在textarea光标处插入表情字符

/**
* 在光标的位置插入图片
* @param {Object} myField  textarea的Id
* @param {Object} myValue  插入的字符
*/

function AddOnPos(myField, myValue)
{
//IE support
if (document.selection)
{
myField.focus();
sel = document.selection.createRange();
myValue = "{"+myValue+"}";
sel.text = myValue;
sel.select();
}

//MOZILLA/NETSCAPE support
else if (myField.selectionStart || myField.selectionStart == '0')
{
var startPos = myField.selectionStart;
var endPos = myField.selectionEnd;
// save scrollTop before insert
var restoreTop = myField.scrollTop;
myValue = "[face]"+myValue+"[/face]";
myField.value = myField.value.substring(0, startPos) + myValue + myField.value.substring(endPos,myField.value.length);
if (restoreTop > 0)
{
// restore previous scrollTop
myField.scrollTop = restoreTop;
}
myField.focus();
myField.selectionStart = startPos + myValue.length;
myField.selectionEnd = startPos + myValue.length;
} else {
myField.value += myValue;
myField.focus();
}
}