[英]NodeJs: fs.appendFile function seems to miss last String given
我是NodeJS的新手,我嘗試了append函數。 當我在下面的代碼中運行時,僅在提示用戶之后輸入用戶輸入,然后將其添加到收藏夾中,並放入帶有歌手名稱的文件。 並附加收藏歌曲,似乎如果用戶輸入退出應將其附加到文件,但不是??? 同時,如果添加了對appendFileSync(fn的同步版本)的更改,則退出?
碼:
var readline = require ('readline');
var fs = require('fs');
var rl = readline.createInterface(process.stdin, process.stdout);
var singer = {
name:'',
songs: []
};
rl.question("What is your fav singer? ", function(answer) {
singer.name = answer;
//creating a file for this singer
fs.writeFileSync(singer.name+".md", `${singer.name}\n====================\n\n`);
rl.setPrompt(`What's your fav songs for ${singer.name} ?`);
rl.prompt();
rl.on('line', function(song) {
singer.songs.push(song.trim());
fs.appendFile(singer.name+".md", `* ${song.trim()} \n`);
//***** WHY IF ITS EXIT ITS NEVER APPEND IT TO THE FILE
console.log(`* ${song.trim()} \n`);
if (song.toLowerCase().trim() === 'exit') {
fs.appendFile(singer.name+".md", "Bye");
//***** WHY ITS NEVER APPEND IT TO THE FILE
rl.close();
} else {
rl.setPrompt(`what else would ${singer.name} say? ('exit'to leave)`);
rl.prompt();
}
});
});
rl.on ('close', function() {
console.log ("%s is a real person that says %j", singer.name, singer.songs);
process.exit();
});
因為fs.appendFile
是異步的。 當您調用它時,io操作僅排隊。 不幸的是,您的腳本在真正的io操作發生之前就退出了。
所以。 您必須將fs.appendFileSync
或fs.appendFile
與回調(第3個參數)一起使用,並在調用回調時執行所有進一步的操作。
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