function replaceSelection() {

            if (window.getSelection) {

                var selecter = window.getSelection();

                var selectStr = selecter.toString();

                if (selectStr.trim != "") {

                    var rang = selecter.getRangeAt(0);

                    var temp = $("<b>" + selectStr + "<b/>");

                    rang.surroundContents(temp[0]);

                }

            } else if (document.selection) {//ie

                var selecter = document.selection.createRange();

                selecter.select();

                var selectStr = selecter.text;

                selecter.pasteHTML("<b>" + selectStr + "<b/>");

            }

        }