For循环不等待await

Question

我正在使用“for of”循环。但它仍然没有等待虚拟函数退出。我假设等待会等待“虚拟”函数完成，然后使用“for of”。

日志输出：

End wait true
starting wait
End wait true
starting wait
End wait true
I am waiting for 925.6301720227887
I am waiting for 923.6969211579702
I am waiting for 962.0987671698102
etc...



const dummy = async(timeToWait) => {
    await setTimeout(() => {
        console.log("I am waiting for", timeToWait);

    }, timeToWait);
    return Promise.resolve(true);
}

    // Iterate over the minutes off and get aggregate data
    const computeAggregate = async (model, sym) => {


    await model.find({"symbol": sym})
    .sort({trade_ts:1}).exec()
    .then(async (symbol) => {
        var firstDoc = symbol[0];
        currentMinute = symbol[0].minutes_offs;
        var rec = [];

        for (sym of symbol) {

            console.log("starting wait");
            let val = await dummy(Math.random() * 1000);
            console.log("End wait", val);
            }
        }

    });

}

Answer 1

您的dummy函数是错误的 \xe2\x80\x93setTimeout不会返回任何可等待的内容，因此它会立即返回。

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由 Promise 驱动的delay函数看起来像

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const delay = timeToWait => new Promise(resolve => setTimeout(resolve, timeToWait));\n

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所以尝试用它代替你的dummy, ie

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console.log(\'hello\');\nawait delay(100);\nconsole.log(\'world\');\n

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编辑：总而言之，您的代码可能应该看起来像

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const delay = timeToWait => new Promise(resolve => setTimeout(resolve, timeToWait));\n// Iterate over the minutes off and get aggregate data\nconst computeAggregate = async (model, sym) => {\n  const symbols = await model\n    .find({ symbol: sym })\n    .sort({ trade_ts: 1 })\n    .exec();\n  const currentMinute = symbols[0].minutes_offs;\n  for (let sym of symbols) {\n    await delay(Math.random() * 1000);\n    console.log("End wait", val);\n  }\n};\n

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所以你没有混合await和.then()。

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