我有一些正在尝试运行的示例代码,并且我希望同步调用一些正在执行的异步函数。 我知道您需要向函数添加异步才能进行等待。我已经这样做了。尽管如此,我还是收到以下错误:
let result = await promise;
^^^^^
SyntaxError: await is only valid in async function
at new Script (vm.js:80:7)
at createScript (vm.js:274:10)
at Object.runInThisContext (vm.js:326:10)
at Module._compile (internal/modules/cjs/loader.js:664:28)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
at Module.load (internal/modules/cjs/loader.js:600:32)
at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
at Function.Module._load (internal/modules/cjs/loader.js:531:3)
at Function.Module.runMain (internal/modules/cjs/loader.js:754:12)
at startup (internal/bootstrap/node.js:283:19)
对于上下文,这是我的代码:
async function main() {
var client = Client.fromConnectionString(deviceConnectionString, Protocol);
fs.stat(filePath, function (err, fileStats) {
var fileStream = fs.createReadStream(filePath);
for (var i=0;i<10;i++) {
let promise = new Promise((res, rej) => {
client.uploadToBlob('testblob.txt', fileStream, fileStats.size, function (err, result) {
if (err) {
console.error('error uploading file: ' + err.constructor.name + ': ' + err.message);
} else {
console.log('Upload successful - ' + result);
}
res(i);
});
})
let result = await promise;
console.log(result);
}
fileStream.destroy();
});
}
main();
当我的函数已经异步时,为什么我会收到上述错误?
最佳答案
您正在尝试在未标记为 async(您的回调)的函数内使用 async-await。
只需将回调设为异步等待函数即可。
async function main() {
var client = Client.fromConnectionString(deviceConnectionString, Protocol);
fs.stat(filePath, async function (err, fileStats) {
var fileStream = fs.createReadStream(filePath);
for (var i=0;i<10;i++) {
let promise = new Promise((res, rej) => {
client.uploadToBlob('testblob.txt', fileStream, fileStats.size, function (err, result) {
if (err) {
console.error('error uploading file: ' + err.constructor.name + ': ' + err.message);
} else {
console.log('Upload successful - ' + result);
}
res(i);
});
})
let result = await promise;
console.log(result);
}
fileStream.destroy();
});
}
main();
关于javascript - 即使await位于Node.js中的异步函数中,如何修复 "await is only valid in async function"?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/57422318/