textarea-helper.js

(function ($) {
  insertAtCaret = function (areaId, text) {
    var txtarea = document.getElementById(areaId);
    var scrollPos = txtarea.scrollTop;
    var strPos = 0;
    var br =
      txtarea.selectionStart || txtarea.selectionStart == "0"
        ? "ff"
        : document.selection
        ? "ie"
        : false;
    if (br == "ie") {
      txtarea.focus();
      var range = document.selection.createRange();
      range.moveStart("character", -txtarea.value.length);
      strPos = range.text.length;
    } else if (br == "ff") strPos = txtarea.selectionStart;

    var front = txtarea.value.substring(0, strPos);
    var back = txtarea.value.substring(strPos, txtarea.value.length);
    txtarea.value = front + text + back;
    strPos = strPos + text.length;
    if (br == "ie") {
      txtarea.focus();
      range = document.selection.createRange();
      range.moveStart("character", -txtarea.value.length);
      range.moveStart("character", strPos);
      range.moveEnd("character", 0);
      range.select();
    } else if (br == "ff") {
      txtarea.selectionStart = strPos;
      txtarea.selectionEnd = strPos;
      txtarea.focus();
    }
    txtarea.scrollTop = scrollPos;
  };

  $.fn.getCursorPosition = function () {
    var el = $(this).get(0);
    var pos = 0;
    if ("selectionStart" in el) {
      pos = el.selectionStart;
    } else if ("selection" in document) {
      el.focus();
      var Sel = document.selection.createRange();
      var SelLength = document.selection.createRange().text.length;
      Sel.moveStart("character", -el.value.length);
      pos = Sel.text.length - SelLength;
    }
    return pos;
  };

  $.fn.setCursorPosition = function (pos) {
    if ($(this).get(0).setSelectionRange) {
      $(this).get(0).setSelectionRange(pos, pos);
    } else if ($(this).get(0).createTextRange) {
      var range = $(this).get(0).createTextRange();
      range.collapse(true);
      range.moveEnd("character", pos);
      range.moveStart("character", pos);
      range.select();
    }
  };
})(jQuery);