如何获取文本框中插入符号的(x,y)像素坐标?

meteor-autocomplete textarea-caret-position

• two bugs
• "ghost" position in the empty space

http://jsfiddle.net/dandv/aFPA7/

<div> <textarea> <span>

document.selection TextRange

function insertAtCursor(myField, myValue) {

/* selecion model - ie */
if (document.selection) {
  myField.focus();
  sel = document.selection.createRange();
  sel.text = myValue;
}

/* field.selectionstart/end  firefox */ 
else if (myField.selectionStart || myField.selectionStart == '0' ) {

  var startPos = myField.selectionStart;
  var endPos = myField.selectionEnd;
  myField.value = myField.value.substring(0, startPos)
    + myValue
    + myField.value.substring(endPos, myField.value.length);

  myField.selectionStart = startPos + myValue.length;
  myField.selectionEnd = startPos + myValue.length;
  myField.focus();
} 

// cursor not active/present
else {
  myField.value += myValue;
}

http://msdn.microsoft.com/en-us/library/ms535869(VS.85).aspx
http://msdn.microsoft.com/en-us/library/ms535872(VS.85).aspx

Here's a blog post from 2005