//启用javascript 日志功能
var logger = log4javascript.getLogger("main");
log4javascript.setEnabled(true);

var appender = new log4javascript.InPageAppender();
appender.layout.pattern = ‘%d{yyyy-MM-dd HH:mm:ss,SSS} [%c] %-5p - %m{1}%n‘;
logger.addAppender(appender);

//点击Ctrl键时显示/隐藏日志控制台
document.onkeydown = function (evt) {
    var VK_F9 = 120;
    //兼容IE和Firefox获得keyBoardEvent对象
    var evt = (evt) ? evt : ((window.event) ? window.event : "");
    //兼容IE和Firefox获得keyBoardEvent对象的键值
    var key = evt.keyCode ? evt.keyCode : evt.which;

    if (evt.ctrlKey) {
        if (appender.visible) {
            appender.hide();
            appender.visible = false;
            log4javascript.setEnabled(false);
        } else {
            log4javascript.setEnabled(true);
            appender.show();
            appender.visible = true;
        }
    }
};

<script src="~/Content/Third/log4javascript-1.4.2/log4javascript.js"></script>
<script src="~/Scripts/Common/log4jsService.js"></script>

  $(function () {
        $("#Button1").click(function () {
            logger.debug("This is a debugging message from the log4javascript in-page page");
            logger.info("info info");
            logger.error("error info");
        });
    });