如何更新json文件中的值并通过node.js保存

问题描述：

如何更新json文件中的值并通过node.js保存? 我有文件内容:

How do I update a value in a json file and save it through node.js? I have the file content:

var file_content = fs.readFileSync(filename);
var content = JSON.parse(file_content);
var val1 = content.val1;

现在，我想更改val1的值并将其保存到文件中.

Now I want to change the value of val1 and save it to the file.

答

异步进行此操作非常容易.如果您担心(可能)阻塞线程，则该功能特别有用.

Doing this asynchronously is quite easy. It's particularly useful if you're concerned for blocking the thread (likely).

var fs = require('fs');
var fileName = './file.json';
var file = require(fileName);

file.key = "new value";

fs.writeFile(fileName, JSON.stringify(file), function (err) {
  if (err) return console.log(err);
  console.log(JSON.stringify(file));
  console.log('writing to ' + fileName);
});

需要注意的是，json是在一行中写入到文件中的，没有经过修饰.例如:

The caveat is that json is written to the file on one line and not prettified. ex:

{
  "key": "value"
}

将是...

{"key": "value"}

为避免这种情况，只需将这两个额外的参数添加到JSON.stringify

To avoid this, simply add these two extra arguments to JSON.stringify

JSON.stringify(file, null, 2)

null-表示替换器功能. (在这种情况下，我们不想更改流程)

null - represents the replacer function. (in this case we don't want to alter the process)

2-表示要缩进的空格.

2 - represents the spaces to indent.

如何更新json文件中的值并通过node.js保存

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