Node.js如何在main.js动态设置环境变量供所有文件读取？

我有多份运行测试并将结果写入日志的脚本，还有用于创建、更新日志的辅助函数。希望根据脚本运行时间动态命名日志文件，因此需要在触发所有测试的main.js中存储文件名变量，并让helper-functions.js中的函数都能访问它。

尝试在main.js中设置环境变量process.env.LOGFILE，发现createLogs函数可以读取，但导出到其他文件的updateLogs函数无法读取。不过在helper-functions.js中硬编码该环境变量时，两个辅助函数都能正常使用。请问如何在main.js中动态设置process.env.LOGFILE并让所有辅助函数都能读取？（注：因安全限制无法使用第三方包）

现有代码 #

main.js #

const d = new Date();
const logName = "fooBar";
process.env.LOGFILE = logName + "-" + d.getDay() + "-" + d.getMonth() + "-" + d.getFullYear()  +  ".json";
createLogs(logName);

// Running tests on other files...

helper-functions.js #

//If I uncomment the below it works, but file name is hard coded.
//process.env.LOGFILE = "customLogs.json";
    
//Create log file when scripts are first run
const createLogs = (logName) => {
    exec('git branch --show-current', (err, stdout, stderr) => {
        if (err) {
            console.log("Error getting git branch:" + stderr);
        }

        const startTime = ((Date()).toLocaleString()).split('GMT')[0];
        const branchName = stdout ? stdout.replace(/(\r\n|\n|\r)/gm,"") : "no-branch";

        let repObjString = `{"details":{"name": "${logName}","time": "${startTime}","branch": "${branchName}"},"report":{}}`;

        const logFileName = `logs/${process.env.LOGFILE}`; //<== THIS WORKS
        if (!fs.existsSync(logFileName)) {
            console.log("Log doesnt exist. Making one...");
            fs.writeFile(logFileName, repObjString, function (err) {
                if (err) throw err;
                console.log('Creating file!');
            });
        }
    });
}

// Update logs
const updateLogs = (logObj) => {
    const logName = `logs/${process.env.LOGFILE}`; //<== THIS DOES NOT WORK

    fs.readFile(logName, 'utf8', function (err, logData) {
        if (err) throw err;
        Object.assign(logData["report"], logObj);
        fs.writeFile (logName, logData, function(err) {
            if (err) throw err;
            console.log('Log updated');
        });
    });
}

方法1：直接传递文件名参数（最可靠） #

避免依赖环境变量，直接将动态生成的文件名作为参数传递给createLogs和updateLogs，这是最直观且不易出问题的方式：

修改helper-functions.js #

//Create log file when scripts are first run
const createLogs = (logName, logFileName) => { // 添加logFileName参数
    exec('git branch --show-current', (err, stdout, stderr) => {
        if (err) {
            console.log("Error getting git branch:" + stderr);
        }

        const startTime = ((Date()).toLocaleString()).split('GMT')[0];
        const branchName = stdout ? stdout.replace(/(\r\n|\n|\r)/gm,"") : "no-branch";

        let repObjString = `{"details":{"name": "${logName}","time": "${startTime}","branch": "${branchName}"},"report":{}}`;

        const fullLogPath = `logs/${logFileName}`; // 使用传入的参数
        if (!fs.existsSync(fullLogPath)) {
            console.log("Log doesnt exist. Making one...");
            fs.writeFile(fullLogPath, repObjString, function (err) {
                if (err) throw err;
                console.log('Creating file!');
            });
        }
    });
}

// Update logs
const updateLogs = (logObj, logFileName) => { // 添加logFileName参数
    const fullLogPath = `logs/${logFileName}`; // 使用传入的参数

    fs.readFile(fullLogPath, 'utf8', function (err, logData) {
        if (err) throw err;
        // 修复bug：读取的logData是字符串，需先转为JSON对象
        const parsedLogData = JSON.parse(logData);
        Object.assign(parsedLogData.report, logObj);
        fs.writeFile(fullLogPath, JSON.stringify(parsedLogData), function(err) {
            if (err) throw err;
            console.log('Log updated');
        });
    });
}

// 导出函数
module.exports = { createLogs, updateLogs };

修改main.js #

const d = new Date();
const logName = "fooBar";
const logFileName = logName + "-" + d.getDay() + "-" + d.getMonth() + "-" + d.getFullYear()  +  ".json";
const { createLogs } = require('./helper-functions');
createLogs(logName, logFileName);

// 运行测试时，调用updateLogs需传递logFileName
// 示例：const { updateLogs } = require('./helper-functions');
// updateLogs(testResult, logFileName);

方法2：在辅助模块中导出可修改的文件名变量 #

在helper-functions.js中定义可导出的变量，main.js中设置该变量的值，所有辅助函数直接访问该变量：

修改helper-functions.js #

// 定义可导出的文件名变量
let logFileName = '';

//Create log file when scripts are first run
const createLogs = (logName) => {
    exec('git branch --show-current', (err, stdout, stderr) => {
        if (err) {
            console.log("Error getting git branch:" + stderr);
        }

        const startTime = ((Date()).toLocaleString()).split('GMT')[0];
        const branchName = stdout ? stdout.replace(/(\r\n|\n|\r)/gm,"") : "no-branch";

        let repObjString = `{"details":{"name": "${logName}","time": "${startTime}","branch": "${branchName}"},"report":{}}`;

        const fullLogPath = `logs/${logFileName}`; // 使用模块内变量
        if (!fs.existsSync(fullLogPath)) {
            console.log("Log doesnt exist. Making one...");
            fs.writeFile(fullLogPath, repObjString, function (err) {
                if (err) throw err;
                console.log('Creating file!');
            });
        }
    });
}

// Update logs
const updateLogs = (logObj) => {
    const fullLogPath = `logs/${logFileName}`; // 使用模块内变量

    fs.readFile(fullLogPath, 'utf8', function (err, logData) {
        if (err) throw err;
        const parsedLogData = JSON.parse(logData);
        Object.assign(parsedLogData.report, logObj);
        fs.writeFile(fullLogPath, JSON.stringify(parsedLogData), function(err) {
            if (err) throw err;
            console.log('Log updated');
        });
    });
}

// 导出变量和函数
module.exports = { createLogs, updateLogs, logFileName };

修改main.js #

const d = new Date();
const logName = "fooBar";
const { createLogs, logFileName: helperLogFileName } = require('./helper-functions');
// 设置辅助模块中的文件名变量
helperLogFileName = logName + "-" + d.getDay() + "-" + d.getMonth() + "-" + d.getFullYear()  +  ".json";
createLogs(logName);

// 其他测试文件导入后可直接使用，无需重复传递

方法3：确保模块加载顺序（修复环境变量问题） #

如果坚持使用环境变量，问题大概率是其他导入updateLogs的模块，在main.js设置process.env.LOGFILE之前就加载了helper-functions.js。需保证main.js是程序入口，先设置环境变量再导入其他模块：

修改main.js #

// 第一步：先设置环境变量
const d = new Date();
const logName = "fooBar";
process.env.LOGFILE = logName + "-" + d.getDay() + "-" + d.getMonth() + "-" + d.getFullYear()  +  ".json";

// 第二步：再导入辅助函数和测试模块
const { createLogs } = require('./helper-functions');
createLogs(logName);

// 最后导入并运行测试
require('./test-module-1');
require('./test-module-2');

这样所有后续导入的模块，包括它们引用的helper-functions.js，都会读取到已设置好的环境变量。

内容的提问来源于stack exchange，提问作者MeltingDog