Node.js fsPromises.readFile()方法

原文:https://www . geesforgeks . org/node-js-fspromises-read file-method/

使用 fsPromises.readFile() 方法读取文件。这个方法将整个文件读入缓冲区。要加载 fs 模块，我们使用 require()方法。它异步读取文件的全部内容。

语法:

fsPromises.readFile( path, options )

参数:该方法接受两个参数，如上所述，如下所述:

  • Path: It saves the name of the file to be read. If it is stored in another location, it saves the whole path. It is a string, buffer, web address or file name.
  • Option : Save the file code. Its default value is "utf8". It is an object or a string.
    • Code: is a string or empty. Default: blank
    • Flag: A string supporting the file system flag. Default value: "r".

返回值:返回承诺。

  • Promise to solve it with the contents of the document. If no encoding is specified (using options.encoding), the data will be returned as a buffer object. Otherwise, the data will be a string.
  • If the option is a string, it specifies the encoding.
  • When the path is a directory, the behavior of fspromises.readfile () is platform specific. On MAC OS, Linux and Windows, promise will be rejected with errors. On FreeBSD, a representation of the contents of the directory will be returned.

下面的例子说明了 Node.js 中的 fsPromises.readFile() 方法:

创建一个演示文本文件，就像，我们已经创建了 GFG.txt 与以下文本:

Greetings from GeeksforGeeks

文件名:

// Node.js program to demonstrate 
// the fsPromises.readFile() method 

// Include fs module 
var fs = require('fs'); 
const fsPromises = require('fs').promises;

// Use fsPromises.readFile() method
// to read the file 
fs.promises.readFile("./GFG_Test.txt")
.then(function(result) {
  console.log(""+result);
})
.catch(function(error) {
   console.log(error);
})

运行该程序的步骤:从根目录运行以下命令，如下所示:

node index.js

输出:

Greetings from GeeksforGeeks

参考:https://nodejs . org/API/fs . html # fs _ fspromises _ readfile _ path _ options

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