cannot solve ts error: object is possibly undefined error

Question

我的代码如下所示，我在 telemetryData .get(cid) 下不断收到带有红线的 'object is possibly undefined' 错误。不确定如何解决这个问题？谢谢！

const updateLoadedCount = mutatorAction('updateLoadedCount', (cid: string) => {
    const telemetryData = getTelemetryStore()?.telemetryData;
    if (telemetryData?.has(cid)) {
        if (telemetryData .get(cid) !== undefined) {
            telemetryData .get(cid).imageLoaded =
                telemetryData .get(cid).imageLoaded + 1;
        }
    }
})

Answer 1

您需要将 telemtryData.get(cid) 赋值给一个值，然后检查它是否未定义（或无效或错误）。 TypeScript 不会知道某些条件不会在下次调用时更改 telemtryData.get(cid) 的结果。

const updateLoadedCount = mutatorAction('updateLoadedCount', (cid: string) => {
    const telemetryData = getTelemetryStore()?.telemetryData;
    const cidValue = telemetryData?.get(cid);
    if (cidValue !== undefined) {
        cidValue.imageLoaded += 1;
    }
})

cannot solve ts error: object is possibly undefined error

cannot solve ts error: object is possibly undefined error

typescript

tslint