javascript - 确定 Promises.all 中哪个 Promise 最慢

Question

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

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

Answer 1

您可以使用辅助函数来实现:

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"),
]);