node.js 使用 fs.writeFileSync 将 JSON 对象写入 JSON 文件
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/42179037/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Writing JSON object to a JSON file with fs.writeFileSync
提问by Romulus3799
I am trying to write a JSON object to a JSON file. The code executes without errors, but instead of the content of the object been written, all that gets written into the JSON file is:
我正在尝试将 JSON 对象写入 JSON 文件。代码执行没有错误，但不是写入对象的内容，而是写入 JSON 文件的所有内容是：
[object Object]
This is the code that actually does the writing:
这是实际编写的代码：
fs.writeFileSync('../data/phraseFreqs.json', output)
'output' is a JSON object, and the file already exists. Please let me know if more information is required.
'output' 是一个 JSON 对象，该文件已经存在。如果需要更多信息，请告诉我。
回答by Kamal
You need to stringify the object.
您需要对对象进行字符串化。
fs.writeFileSync('../data/phraseFreqs.json', JSON.stringify(output));
回答by akinjide
I don't think you should use the synchronous approach, asynchronously writing data to a file is better also stringify the outputif it's an object.
我认为您不应该使用同步方法，将数据异步写入文件最好也将output其字符串化，如果它是object.
Note: If outputis a string, then specify the encoding and remember the flagoptions as well.:
注意：如果output是字符串，则指定编码并记住flag选项。：
const fs = require('fs');
const content = JSON.stringify(output);
fs.writeFile('/tmp/phraseFreqs.json', content, 'utf8', function (err) {
if (err) {
return console.log(err);
}
console.log("The file was saved!");
});
Added Synchronous method of writing data to a file, but please consider your use case. Asynchronous vs synchronous execution, what does it really mean?
添加了将数据写入文件的同步方法，但请考虑您的用例。异步与同步执行，到底是什么意思？
const fs = require('fs');
const content = JSON.stringify(output);
fs.writeFileSync('/tmp/phraseFreqs.json', content);
回答by Timelot
Make the json human readable by passing a third argument to stringify:
通过将第三个参数传递给 json 使 json 可读stringify：
fs.writeFileSync('../data/phraseFreqs.json', JSON.stringify(output, null, 4));
回答by Reza Baradaran Gazorisangi
When sending data to a web server, the data has to be a string (here). You can convert a JavaScript object into a string with JSON.stringify().
Hereis a working example:
向 Web 服务器发送数据时，数据必须是字符串（此处）。您可以使用 .js 将 JavaScript 对象转换为字符串JSON.stringify()。
这是一个工作示例：
var fs = require('fs');
var originalNote = {
title: 'Meeting',
description: 'Meeting John Doe at 10:30 am'
};
var originalNoteString = JSON.stringify(originalNote);
fs.writeFileSync('notes.json', originalNoteString);
var noteString = fs.readFileSync('notes.json');
var note = JSON.parse(noteString);
console.log(`TITLE: ${note.title} DESCRIPTION: ${note.description}`);
Hope it could help.
希望它能有所帮助。
回答by Flimm
Here's a variation, using the version of fsthat uses promises:
这是一个变体，使用fs使用 promise的版本：
const fs = require('fs');
await fs.promises.writeFile('../data/phraseFreqs.json', JSON.stringify(output)); // UTF-8 is default
