我有这样一个函数，它创建一个写流，然后将字符串数组写入文件。一旦写完，我想让它回报一个承诺。但我不知道该怎么做。
function writeToFile(filePath: string, arr: string[]): Promise<boolean> {
const file = fs.createWriteStream(filePath);
arr.forEach(function(row) {
file.write(row + "\n");
});
file.end();
file.on("finish", ()=>{ /*do something to return a promise but I don't know how*/});
}
谢谢您的任何评论！
您需要使用promise构造函数:
function writeToFile(filePath: string, arr: string[]): Promise<boolean> {
return new Promise((resolve, reject) => {
const file = fs.createWriteStream(filePath);
for (const row of arr) {
file.write(row + "\n");
}
file.end();
file.on("finish", () => { resolve(true); }); // not sure why you want to pass a boolean
file.on("error", reject); // don't forget this!
});
}
在完成操作之前，您需要返回承诺。
类似于:
function writeToFile(filePath: string, arr: string[]): Promise<boolean> {
return new Promise((resolve, reject) => {
const file = fs.createWriteStream(filePath);
arr.forEach(function(row) {
file.write(row + "\n");
});
file.end();
file.on("finish", () => { resolve(true) });
});
}
