Question

我是Node的新手，试图理解回调和Promise。我正在使用开放源代码HTTP基准测试模块从特定URL提取数据并在获取数据后处理结果。这是我的代码

'use strict'

const autocannon = require('autocannon')

const instance = autocannon({
        url: 'http://localhost:3000',
        connections: 5,
        duration: 5
}, (err, result) => handleResults(result))

async function handleResults (res){
    try{
        let abReport = [];
        abReport.push(
          'Test Completed:' + '\n' +
          'Time taken for tests:' + res.duration + '\n' +
          'Total Concurrent Connections:' + res.connections + '\n' +
          'URL:' + res.url + '\n' +
          'Total Errors:' + res.errors + '\n' +
          'Total Timeouts:' + res.timeouts + '\n'
        )
        console.log(abReport.join('\n'));
    }
    catch(error) {
            console.error(error);
    }
}

autocanon会将输出传递到handleResults，但是handleResults出错并显示错误TypeError: Cannot read property 'duration' of undefined。我正在尝试寻找一种方法，仅在从自动炮成功传递值之后，才能处理handleResults。

Answer 1

将(err, result) => handleResults(result)更改为

(err, result) => {
   if (err != null) return; // or do some error handling
   handleResults(result);
}

Answer 2

我使用下面的代码来工作：

'use strict'

const autocannon = require('autocannon');

const getAbReport  = async () => {
    try {
        const instance = await autocannon({
            url: 'http://localhost:3000',
            connections: 5,
            duration: 5
        }, (err, result) => handleResults(result));
    } catch(error) {
        console.log(error);
    }
}

async function handleResults(result) {
    try{
        let abReport = [];
        abReport.push(
          'Test Completed:' + '\n' +
          'Time taken for tests:' + result.duration + '\n' +
          'Total Concurrent Connections:' + result.connections + '\n' +
          'URL:' + result.url + '\n' +
          'Total Errors:' + result.errors + '\n' +
          'Total Timeouts:' + result.timeouts + '\n'
        )
        console.log(abReport.join('\n'));
    }
    catch(error) {
        console.error(error);
    }
}

getAbReport();

Answer 3

使用异步等待，您可以更新代码，

'use strict'

const autocannon = require('autocannon');

async function handleResults (res){
    try{
        let abReport = [];
        abReport.push(
          'Test Completed:' + '\n' +
          'Time taken for tests:' + res.duration + '\n' +
          'Total Concurrent Connections:' + res.connections + '\n' +
          'URL:' + res.url + '\n' +
          'Total Errors:' + res.errors + '\n' +
          'Total Timeouts:' + res.timeouts + '\n'
        )
        console.log(abReport.join('\n'));
    }
    catch(error) {
        console.error(error);
    }
}

const getAbReport  = async () => {
    try {
            const result = await autocannon({
            url: 'http://localhost:3000',
            connections: 5,
            duration: 5,
        });
        await handleResults(result);
    } catch(error) {
        console.log(error);
    }
}

getAbReport();

如何等待结果处理？

3 个答案: