javascript - 递归异步到 promise 或回调

Question

问题: 我有一个棘手的情况，我正在递归遍历文件和目录，当文件符合特定条件时，我使用 Node 的 readLine(异步函数)读取该文件的第一行。一旦该行被读取，条目就会被插入一个变量(例如 depTree)。由于我的一些代码是异步的，所以我无法同步获取 depTree 的值。

代码:

const fs = require('fs'); 
const readline = require('readline');
const path = './mycoolpath/';
const depTree = [];

const imports = file => {
    const readLines = readline.createInterface({
        input: fs.createReadStream(file),
        crlfDelay: Infinity
    });
    // read each line, and push line to depTree if it passes my regex criteria
    readLines.on('line', (line) => {
        if (/lineMatchesMyregex/.test(line)) {
            depTree.push(line)
        }
    });
}

const recursiveSearch = path => {
    const files = fs.readdirSync(path);
    for (var i in files) {
        var file = path + '/' + files[i];
        var stats = fs.statSync(file);
        if (stats.isFile()) {
            imports(file);
        }
        else if (stats.isDirectory()) {
            recursiveSearch(file);
        }
    }

};

recursiveSearch(path);

//// embaressing setTimeout
// setTimeout(() => {
//     console.log(depTree)
// }, 1000) 

尝试:

我不得不使用 setTimeout 并且我确信有更好的方法，我修改了回调和 promise 但无济于事。如果有任何帮助/见解，我将不胜感激。

Answer 1

如果您在 Node.js 中使用 async/await 关键字和 promises，您可以按如下方式解决此问题:

const fs = require('fs');
const readline = require('readline');
const path = './mycoolpath/';
const depTree = [];

const imports = file => {
    return new Promise((resolve, reject) => {
        const readLines = readline.createInterface({
            input: fs.createReadStream(file),
            crlfDelay: Infinity
        });
        // read each line, and push line to depTree if it passes my regex criteria
        readLines.on('line', (line) => {
            if (/lineMatchesMyregex/.test(line)) {
                depTree.push(line)
            }
        });
        // once done reading all the lines, resolve the promise
        readLines.on('close', () => {
            resolve();
        })
    });
}

const recursiveSearch = async (path) => {
    const files = fs.readdirSync(path);
    for (var i in files) {
        var file = path + '/' + files[i];
        var stats = fs.statSync(file);
        if (stats.isFile()) {
            await imports(file);
        } else if (stats.isDirectory()) {
            await recursiveSearch(file);
        }
    }

};


//// embaressing setTimeout
setTimeout(async () => {
    await recursiveSearch(path);
    console.log(depTree)
}, 1000)

// or even better, to avoid too long or too short timeout
recursiveSearch(path)
    .then(() => {
        console.log(depTree)
    })