Node.js | fs.appendFileSync()函数
原文:https://www . geesforgeks . org/node-js-fs-appendfilesync-function/
fs.appendFileSync()方法用于将给定数据同步追加到文件中。如果新文件不存在，则会创建一个新文件。可选选项参数可用于修改操作的行为。
语法:
fs.appendFileSync( path, data, options])
参数:该方法接受三个参数，如上所述，如下所述:
- Path: It is a string, buffer, web address or number, which indicates the name of the source file or the file descriptor to be attached.
- Data: is a character string or buffer that indicates the data that must be appended.
- Option: is a string or object that can be used to specify optional parameters that affect output. There are three optional parameters:
- Code: is a string that specifies the file code. The default value is utf8.
- Mode: An integer that specifies the file mode. The default value is "0o666".
- Flag: It is a string that specifies the flag to be used when attaching to a file. The default value is "A".
下面的例子说明了 Node.js 中的 fs.appendFileSync()方法:
示例 1: 该示例显示了给定文本到文件的追加。
// Node.js program to demonstrate the
// fs.appendFileSync() method
// Import the filesystem module
const fs = require('fs');
// Get the file contents before the append operation
console.log("\nFile Contents of file before append:",
fs.readFileSync("example_file.txt", "utf8"));
fs.appendFileSync("example_file.txt", " - Geeks For Geeks");
// Get the file contents after the append operation
console.log("\nFile Contents of file after append:",
fs.readFileSync("example_file.txt", "utf8"));
输出:
File Contents of file before append: Hello
File Contents of file after append: Hello - Geeks For Geeks
示例 2: 该示例显示了可选参数的用法，用于更改操作的文件编码和标志。“w”标志代替文件的内容，而不是附加到它上面。
// Node.js program to demonstrate the
// fs.appendFileSync() method
// Import the filesystem module
const fs = require('fs');
// Get the file contents before the append operation
console.log("\nFile Contents of file before append:",
fs.readFileSync("example_file.txt", "utf8"));
// Append to the file using optional parameters
fs.appendFileSync("example_file.txt",
"This is the appended text",
{ encoding: "utf8", flag: "w" }
);
// Get the file contents after the append operation
console.log("\nFile Contents of file after append:",
fs.readFileSync("example_file.txt", "utf8"));
输出:
File Contents of file before append: This is a test file
File Contents of file after append: This is the appended text
参考:T2【https://nodejs . org/API/fs . html # fs _ fs _ appendfilesync _ path _ data _ options
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