确定Promises.all中最慢的承诺 [英] Determine which promise is slowest in Promises.all

问题描述

我一直在我的应用程序中使用Promise.all。
为了提高应用程序速度，如何确定哪个承诺最慢？

I have been using Promise.all in my app. For the purpose of improving app speed, how to determine which promise is the slowest?

const result = await Promise.all([
          this.props.fetchUser(),
          this.props.cacheResourcesAsync(),
          this.props.initAmplitude(),
          this.props.initAppVariables(),
        ]);

推荐答案

您可以为此使用辅助功能：

You can use a helper function for that:

async function time(p, name) {
    const start = Date.now();
    try {
        return await p;
    } finally {
        const end = Date.now();
        console.log(`${name} took ${end-start}ms`);
    }
}

然后写

const result = await Promise.all([
    time(this.props.fetchUser(), "user"),
    time(this.props.cacheResourcesAsync(), "cacheResources"),
    time(this.props.initAmplitude(), "amplitude"),
    time(this.props.initAppVariables(), "appVars"),
]);

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