fs.writeFile在一个许诺中，异步同步的东西 [英] fs.writeFile in a promise, asynchronous-synchronous stuff

问题描述

我的代码需要一些帮助.我是Node.js的新手，遇到了很多麻烦.

I need some help with my code. I'm new at Node.js and have a lot of trouble with it.

我要做什么:

1)使用Amazon产品(ASIN)获取.txt；

1) Fetch a .txt with Amazon products (ASINs) ;

2)使用 amazon-product-api 包获取所有产品；

2) Fetch all products using the amazon-product-api package;

3)将每个产品保存在.json文件中.

3) Save each product in a .json file.

我的代码无法正常工作.我想我把这些异步的东西弄乱了-救救我吧！

My code is not working. I think I messed up with this asynchronous-synchronous stuff - help me!

var amazon = require('amazon-product-api');
var fs = require('fs');

var client = amazon.createClient({
    awsId: "XXX",
    awsSecret: "XXX",
    awsTag: "888"
});

var array = fs.readFileSync('./test.txt').toString().split('\n');
for (var i = 1; i < array.length; i++) {
     var ASIN = array[i];

    return client.itemLookup({
            domain: 'webservices.amazon.de',
            responseGroup: 'Large',
            idType: 'ASIN',
            itemId: ASIN
        })
        .then(function(results) {
            fs.writeFile(ASIN + '.json', JSON.stringify(results), function(err) {
                if (err) {
                    console.log(err);
                } else {
                    console.log("JSON saved");
                }
            })

            return results;

        }).catch(function(err) {
            console.log(err);
        });
};

推荐答案

截至2019年...

...正确的答案是对 节点中包含的本机fs Promise模块 .升级到Node.js 10或11(主要的云提供商已支持)并执行以下操作:

As of 2019...

...the correct answer is to use async/await with the native fs promises module included in node. Upgrade to Node.js 10 or 11 (already supported by major cloud providers) and do this:

const fs = require('fs').promises;

// This must run inside a function marked `async`:
const file = await fs.readFile('filename.txt', 'utf8');
await fs.writeFile('filename.txt', 'test');

不要使用第三方程序包，也不要编写自己的包装器，这不再是必需的.

Do not use third-party packages and do not write your own wrappers, that's not necessary anymore.

在节点11.14.0之前，您仍然会收到警告，告知该功能是试验性的，但效果很好，是将来的方法.从11.14.0开始，该功能不再是实验性的，并且已经可以投入生产.

Before Node 11.14.0, you would still get a warning that this feature is experimental, but it works just fine and it's the way to go in the future. Since 11.14.0, the feature is no longer experimental and is production-ready.

它也可以工作-但仅在未将此功能标记为实验性的Node.js版本中.

It works, too - but only in Node.js versions where this feature is not marked as experimental.

import { promises as fs } from 'fs';

(async () => {
    await fs.writeFile('./test.txt', 'test', 'utf8');
})();

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