我想知道是否可以跟踪app.js和vendor.js文件的加载时间。
根据ApplicationInsights-JS，要获得页面加载时间，可以使用pageView.properties.duration，尝试以下取自文档的代码片段：

_self.trackPageView = (pageView?: IPageViewTelemetry, customProperties?: ICustomProperties) => {
                try {
                    let inPv = pageView || {};
                    _pageViewManager.trackPageView(inPv, {...inPv.properties, ...inPv.measurements, ...customProperties});

                    if (_self.config.autoTrackPageVisitTime) {
                        _pageVisitTimeManager.trackPreviousPageVisit(inPv.name, inPv.uri);
                    }
                } catch (e) {
                    _throwInternal(
                        eLoggingSeverity.CRITICAL,
                        _eInternalMessageId.TrackPVFailed,
                        "trackPageView failed, page view will not be collected: " + getExceptionName(e),
                        { exception: dumpObj(e) });
                }
            };

您可以参考Capture and view page load times in your Azure web app with Application Insights和页面视图性能管理器.ts