jquery在光标位置插入内容指定内容（input、textarea）通用

<textarea id="content" class="layui-textarea"></textarea>
<li onclick="insertHtml('插入内容')" >插入</li>

$('#content').on('select',function () {
        message.setCaret(this);
    }).on('click',function () {
        message.setCaret(this);
    }).on('keyup',function () {
        message.setCaret(this);
    });
    function insertHtml(val) {
        var textareaStr = $('#content').val();
        message.insertAtCaret($('#content')[0],'{'+val+'}');
    }

    var message = {
        setCaret: function (textObj) {
            if (textObj.createTextRange) {
                textObj.caretPos = document.selection.createRange().duplicate();
            }
        },

        insertAtCaret: function (textObj, textFeildValue) {
            if (document.all) {
                if (textObj.createTextRange && textObj.caretPos) {
                    var caretPos = textObj.caretPos;
                    caretPos.text = caretPos.text.charAt(caretPos.text.length - 1) == ' ' ? textFeildValue + ' ' : textFeildValue;
                } else {
                    textObj.value = textFeildValue;
                }
            } else {
                if (textObj.setSelectionRange) {
                    var rangeStart = textObj.selectionStart;
                    var rangeEnd = textObj.selectionEnd;
                    var tempStr1 = textObj.value.substring(0, rangeStart);
                    var tempStr2 = textObj.value.substring(rangeEnd);
                    textObj.value = tempStr1 + textFeildValue + tempStr2;
                } else {
                    alert("此版本的Mozilla浏览器不支持setSelectionRange");
                }
            }
        }
    }