Node.js fs.unwatchFile()方法
原文:https://www . geesforgeks . org/node-js-fs-unwatchfile-method/
fs.unwatchFile()方法用于停止监视给定文件的更改。可以指定可选的侦听器参数，以便仅从文件中移除指定的侦听器。否则，与该文件关联的所有侦听器都将被删除。如果在使用该函数时文件没有被监视，那么它不会执行任何操作并抛出任何错误。
语法:
fs.unwatchFile(filename[, listener])
参数:该方法接受两个参数，如上所述，如下所述:
- File name: It is a string, buffer or web address, which indicates the file that must be stopped.
- Listener: It is a function that specifies the listener that was previously attached using the fs.watchFile () function. If specified, only that specific listener is removed. This is an optional parameter.
下面的例子说明了 Node.js 中的 fs.unwatchFile()方法
例 1:
// Node.js program to demonstrate the
// fs.unwatchFile() method
// Import the filesystem module
const fs = require('fs');
// Start watching the file
fs.watchFile("example_file.txt", (curr, prev) => {
console.log("\nThe file was edited");
console.log("Previous Modified Time:", prev.mtime);
console.log("Current Modified Time:", curr.mtime);
});
// Make Changes to the file before
// it has been stopped watching
setTimeout(
() => fs.writeFileSync("example_file.txt",
"File Contents are Edited"),
1000
);
// Stop watching the file
setTimeout(() => {
fs.unwatchFile("example_file.txt");
console.log("\n> File has been stopped watching");
}, 6000);
// Make Changes to the file after
// it has been stopped watching
setTimeout(
() => fs.writeFileSync("example_file.txt",
"File Contents are Edited Again"),
7000
);
输出:
The file was edited
Previous Modified Time: 2020-05-30T08:43:28.216Z
Current Modified Time: 2020-05-30T08:43:37.208Z
File has been stopped watching
例 2:
// Node.js program to demonstrate
// the fs.unwatchFile() method
// Import the filesystem module
const fs = require('fs');
// Defining 2 listeners for watching the file
let listener1 = (curr, prev) => {
console.log("Listener 1: File Modified");
};
let listener2 = (curr, prev) => {
console.log("Listener 2: File Modified");
};
// Using both the listeners on one file
fs.watchFile("example_file.txt", listener1);
fs.watchFile("example_file.txt", listener2);
// Modify the file contents
setTimeout(
() => fs.writeFileSync("example_file.txt",
"File Contents are Edited"),
1000
);
// Stop using the first listener
setTimeout(() => {
fs.unwatchFile("example_file.txt", listener1);
console.log("\n> Listener 1 has been stopped!\n");
}, 6000);
// Modify the file contents again
setTimeout(
() => fs.writeFileSync("example_file.txt",
"File Contents are Edited Again"),
8000
);
输出:
Listener 1: File Modified
Listener 2: File Modified
Listener 1 has been stopped!
Listener 2: File Modified
参考:https://nodejs . org/API/fs . html # fs _ fs _ unwatchfile _ filename _ listener
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