JavaScript forEach：如何计算 forEach 函数写入的行数？

Question

目前我的代码是：

var ProxyVerifier = require('proxy-verifier');
const fs = require('fs');
var request = require('request');
const { doesNotMatch } = require('assert');

let config = {
    file: 'socks4_proxies.txt',
    destFile: 'result.txt'
}

function countFileLines(filePath) {
    return new Promise((resolve, reject) => {
        let lineCount = 0;
        fs.createReadStream(filePath)
            .on("data", (buffer) => {
                let idx = -1;
                lineCount--; // Because the loop will run once for idx=-1
                do {
                    idx = buffer.indexOf(10, idx + 1);
                    lineCount++;
                } while (idx !== -1);
            }).on("end", () => {
                resolve(lineCount);
            }).on("error", reject);
    });
};

function getProxies() {
    return new Promise(function (resolve, reject) {
        request.get('https://api.proxyscrape.com/?request=displayproxies&proxytype=socks4&timeout=2500', function (error, response, body) {
            if (!error && response.statusCode == 200) {
                resolve(body);
                console.log('Proxies pulled!')
            } else {
                console.log(`Oops, ProxyScrape is down! Please try again later / contact me`)
            }
        });
    });
}

async function proxyTestLogic(proxy_list, index) {
    var countLines = await countFileLines('file.txt')
    console.log(index)
    if (index > 150) {
        console.log('Ok good done you can stop now')
        return 'stop';
    } else {
        var splitProxy = proxy_list.split(':');
        var ipPortArr = [splitProxy[0], Number(splitProxy[1])]
        var proxy = {
            ipAddress: ipPortArr[0],
            port: ipPortArr[1],
            protocol: 'socks4'
        };

        ProxyVerifier.testAll(proxy, function (error, result) {
            if (error) {
            } else {
                if (result["protocols"]["socks4"]["ok"] == true) {
                    fs.appendFile('file.txt', ipPortArr[0] + ':' + ipPortArr[1] + '\n', (err) => {
                    });
                } else {
                }
            }
        });
    }
}

function testProxies(proxies) {
    return new Promise(function (resolve, reject) {
        let newLined = proxies.replace(/\r|\"/gi, '').split("\n")
        newLined.forEach((item, index) => {
            proxyTestLogic(item, index)
        })
    })
}

async function main() {
    let proxies = await getProxies();
    testProxies(proxies)
}

main();

如您所见，它是一个代理验证器。它使用 forEach 函数计算数组中的每个代理。我试图让它停止在写入 socks4_proxies.txt 的 x 行数处，当我在其上启用 console.log 功能时，它只会输出同一行 1200 次（列表中的代理数量）。我该如何解决这个问题？

（我还应该提到我在 node.js 中编码）

谢谢， 吉布西尔

Answer 1

1. 不要在 .forEach 中执行异步代码，这永远不会像您期望的那样工作 - 使用常规 for 循环
2. 使tetProxies异步
3. 使用await proxytestLogic
4. 摆脱 new Promise 反正你永远也解决不了

所以 - 你最终得到：

async function testProxies(proxies) {
    let newLined = proxies.replace(/\r|\"/gi, '').split("\n")
    for (let index=0; i < newLined.length; index++) {
            let result = await proxyTestLogic(newLined[index], index);
            if (result === 'stop')
                break;
        })
    })
}