Node.js fs.filehandle.sync()方法
原文:https://www . geesforgeks . org/node-js-fs-file handle-sync-method/
fs.filehandle.sync() 方法是文件系统模块中类 fs.filehandle 的内置应用编程接口，用于将该文件的内核状态与存储设备同步。 语法:
const filehandle.sync()
参数:此方法不接受任何参数作为参数。 返回值:该方法返回一个不包含任何价值的待定承诺。 下面的程序说明了 fs.filehandle.sync() 方法的使用。 示例 1: 文件名:index.js
java 描述语言
// Node.js program to demonstrate the
// filehandle.sync() method
const fs = require('fs');
const fsPromises = fs.promises;
console.log("content of file before operation :- "
+ (fs.readFileSync('example.txt')));
// Initiating asyncrionise function
async function funct() {
// Initializing following variables
let filehandle = null;
let prom = null;
try {
// Creating and initiating filehandle
filehandle = await
fsPromises.open('example.txt', 'r+');
// Synchronizing the file's in-core state
// by using sync() method
prom = filehandle.sync();
} finally {
if (filehandle) {
// Display the result
console.log("data is synchronized successfully");
console.log("content of file after operation :- "
+ (fs.readFileSync('example.txt')));
// Close the file if it is opened.
await filehandle.close();
}
}
}
funct().catch(console.error);
运行程序前的目录结构:
运行程序后的目录结构:
使用以下命令运行 index.js 文件:
node index.js
输出:
content of file before operation :- Content of file: example.txt
data is synchronized successfully
content of file after operation :- Content of file: example.txt
示例 2: 文件名:index.js
java 描述语言
// Node.js program to demonstrate the
// filehandle.sync() method
const fs = require('fs');
const fsPromises = fs.promises;
// Data for the new file
let data = "This is a file containing"
+ " a collection of books.";
// Name of the file to be created
let file = "books.txt";
// Creating the new file 'books.txt'
fs.writeFile(file, data, (err) => {
// Cathing error
if (err) {
console.log(err);
}
});
// Using fs.exists() method
fs.exists(file, (exists) => {
if (exists) {
console.log("content of file before"
+ " operation :- " +
(fs.readFileSync(file)));
}
});
// Initiating asyncrionise function
async function funct() {
// Initializing filehandle
let filehandle = null;
try {
// Creating and initiating filehandle
filehandle = await
fsPromises.open(file, 'r+');
// Synchronizing the file's in-core
// state by using sync() method
prom = filehandle.sync();
} finally {
if (filehandle) {
// Close the file if it is opened.
console.log("data is synchronized"
+ " successfully");
console.log("content of file after"
+ " operation :- " +
(fs.readFileSync(file)));
await filehandle.close();
}
}
}
funct().catch(console.error);
运行程序前的目录结构:
运行程序后的目录结构:
使用以下命令运行 index.js 文件:
node index.js
输出:
操作前文件的内容:-这是一个包含书籍集合的文件。 数据同步成功 操作后文件内容:-这是一个包含藏书的文件。
参考:T2【https://nodejs . org/dist/latest-v 12 . x/docs/API/fs . html # fs _ file handle _ syncT4】
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