Node.js fs.writeFile()方法

原文:https://www.geeksforgeeks.org/node-js-fs-writefile-method/

fs.writeFile()方法用于将指定的数据异步写入文件。默认情况下，如果文件存在，它将被替换。“选项”参数可用于修改方法的功能。

语法:

fs.writeFile( file, data, options, callback )

参数:这个方法接受上面提到的和下面描述的四个参数:

  • File: It is a string, Buffer, URL or file description integer, indicating the path of the file to which it must be written. Using the file descriptor will make it behave like the fs.write () method.
  • Data: is the string, Buffer, TypedArray or DataView to be written into the file.
  • Option: is a string or object that can be used to specify optional parameters that affect output. It has three optional parameters:
    • Code: is a string value that specifies the file code. The default value is utf8.
    • Mode: An integer value that specifies the file mode. The default value is 0o666.
    • Flag: It is a string value that specifies the flag used when writing to the file. The default value is "w".
  • Callback: is a function that will be called when the method is executed.
    • err: The error that will be thrown if the operation fails.

下面的例子说明了 Node.js 中的 fs.writeFile()方法:

例 1:

// Node.js program to demonstrate the
// fs.writeFile() method

// Import the filesystem module
const fs = require('fs');

let data = "This is a file containing a collection of books.";

fs.writeFile("books.txt", data, (err) => {
  if (err)
    console.log(err);
  else {
    console.log("File written successfully\n");
    console.log("The written has the following contents:");
    console.log(fs.readFileSync("books.txt", "utf8"));
  }
});

输出:

File written successfully

The written has the following contents:
This is a file containing a collection of books.

例 2:

// Node.js program to demonstrate the
// fs.writeFile() method

// Import the filesystem module
const fs = require('fs');

let data = "This is a file containing a collection of movies.";

fs.writeFile("movies.txt", data,
  {
    encoding: "utf8",
    flag: "w",
    mode: 0o666
  },
  (err) => {
    if (err)
      console.log(err);
    else {
      console.log("File written successfully\n");
      console.log("The written has the following contents:");
      console.log(fs.readFileSync("movies.txt", "utf8"));
    }
});

输出:

File written successfully

The written has the following contents:
This is a file containing a collection of movies.

参考:T2【https://nodejs . org/API/fs . html # fs _ fs _ write file _ file _ data _ options _ callback

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