Angular 等待不等待

Question

我有一些带有 await-s 设置的代码，如下所示:

async calculateDeletionResidualsData(res) {
    //console.log("resss is:");
    //console.log(res);

    let selectedCountries = this.countriesList.filter(c => c.selected);
    let selectedIndicators = this.indicatorsList.filter(i => i.selected);

    await selectedCountries.forEach(async c => {
        // taking each (selected) country

        await selectedIndicators.forEach(async i => {
            // taking each (selected) indicator

            // Form the series for the calculation of residuals
            let series = [];
            deletionResidualsRelevantYears.forEach(y => {
                series.push(res[c.label][y][i.label][0]);
            });
            // Calculate deletion residuals
            let drr = await util.calculateDeletionResidualsStatistics(
                deletionResidualsRelevantYears.length,
                series,
                this.deletionResidualsService
            );

            this.drr[c.label][i.label] = drr;
        });
    });

    console.log("setting qrReady to true");
    this.qrReady = true;
}

我可以清楚地看到对 util.calculateDeletionResidualsStatistics 的调用仍在我浏览器的网络选项卡中进行，但我还看到 console.log("setting qrReady to true"); 已经被解雇了，它不应该被解雇。为什么所有这些等待都被跳过并跳到最后一行代码？

Answer 1

await 不适用于使用回调的循环。永远不要将 await 与 forEach 一起使用。改为使用 for 循环(或任何没有回调的循环)

forEach 不是 promise 感知的。它不支持异步和等待。您不能在 forEach 中使用 await。

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