js替换选中的文字

        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/>");
            }
        }