Node.js fs.watchFile()用法及代碼示例

// Node.js program to demonstrate 
// the fs.watchFile() method 
  
// Import the filesystem module 
const fs = require('fs'); 
  
fs.watchFile( 
  
  // The name of the file to watch 
  "example_file.txt", 
  
  // The options parameter is used to  
  //modify the behaviour of the method 
  { 
    // Specify the use of big integers 
    // in the Stats object  
    bigint:false, 
  
    // Specify if the process should  
    // continue as long as file is 
    // watched 
    persistent:true, 
  
    // Specify the interval between 
    // each poll the file 
    interval:4000, 
  }, 
  (curr, prev) => { 
    console.log("\nThe file was edited"); 
  
    // Show the time when the file was modified 
    console.log("Previous Modified Time", prev.mtime); 
    console.log("Current Modified Time", curr.mtime); 
  
    console.log( 
      "The contents of the current file are:", 
      fs.readFileSync("example_file.txt", "utf8") 
    ); 
  } 
); 
  
// Make Changes to the file for the first time 
fs.writeFileSync("example_file.txt", 
   "File Contents are Edited"); 
  
// Make Changes to the file for the second time 
setTimeout( 
  () => fs.writeFileSync("example_file.txt", 
          "File Contents are Edited Again"), 
  5000 
);

// Node.js program to demonstrate  
// the fs.watchFile() method 
  
// Import the filesystem module 
const fs = require('fs'); 
  
fs.watchFile("example_file.txt", (curr, prev) => { 
  console.log("\nThe File was modified"); 
  console.log("Previous Modification Time", prev.mtime); 
  console.log("Current Modification Time", curr.mtime); 
}); 
  
// Renaming the file to a new name 
setTimeout( 
  () => fs.renameSync("example_file.txt", 
           "new_file.txt"), 
  1000 
); 
  
// Renaming the file back to its old name 
setTimeout( 
  () => fs.renameSync("new_file.txt",  
          "example_file.txt"), 
  6000 
);