[英]How can I overwrite and append data to the same file multiple times in node js
我有一個“clients.txt”文件,其中有一個電子郵件列表。 我嘗試運行一個程序來發送電子郵件,我從文件中選擇了一些要使用的電子郵件,在這種情況下,數字是 2。在我使用這兩封電子郵件后,我想在沒有它們的情況下覆蓋“clients.txt”。 問題是當我嘗試只運行一次代碼時,每件事都在工作! 但是如果我做一個循環就會有問題。 期待看到你們的任何幫助。 謝謝! 我在下面添加代碼。 PS:對不起,我的英語不好!
function readEmails(){
const fs = require('fs');
clients_list = fs.readFileSync('clients.txt', 'utf8').split('\n');
let filtered = clients_list.filter(function (el) {
return el != null && el != '';
});
return filtered
}
function dump_array(arr, file){
let fs = require('fs');
let file = fs.createWriteStream(file);
file.on('error', function(err) { /* error handling */ });
arr.forEach(function(v) { file.write(v + '\n'); });
file.end();
}
while_var = 0;
while (while_var < 2){
while_var ++;
let all_clients = readEmails();
let selected_clients = [];
if (all_clients.length > 0){
selected_clients = all_clients.splice(0,2);
dump_array(all_clients, 'clients.txt');
console.log(selected_clients);
}else{
console.log('No more clients')
}
}
const fs = require('fs');
function readEmails(){
const clients_list = fs.readFileSync('clients.txt', 'utf8').split('\n');
const filtered = clients_list
// clear false, 0 and undefined too
.filter(el => !!el)
// remove extra spaces and \r symbols
.map(el => el.trim());
return filtered;
}
function dump_array(arr, file){
// Here you need sync method.
fs.writeFileSync(file, arr.join('\n'));
// And here was 'already declared' error in orginal code
}
let while_var = 0;
while (while_var++ < 2){
let all_clients = readEmails();
let selected_clients = [];
if (all_clients.length > 0){
selected_clients = all_clients.splice(0,2);
dump_array(all_clients, 'clients.txt');
console.log(selected_clients);
}else{
console.log('No more clients')
}
}
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