javascript - 在异步函数上调用await会引发错误(Calling await on an async function throws an error)

Question

I have this function :(我有这个功能：)

async function fileHash(filename, algorithm = 'md5') { return new Promise((resolve, reject) => { // Algorithm depends on availability of OpenSSL on platform // Another algorithms: 'sha1', 'md5', 'sha256', 'sha512' ... let shasum = crypto.createHash(algorithm); try { let s = fs.ReadStream(filename) s.on('data', function (data) { shasum.update(data) }) // making digest s.on('end', function () { const hash = shasum.digest('hex') return resolve(hash); }) } catch (error) { return reject('calc fail'); } }); } But when I use : await fileHash(path, 'sha512');(但是当我使用时： await fileHash(path, 'sha512');) I git this error : await is only valid in async function(我混错了这个错误： await is only valid in async function) Even though the function is an async function.(即使该函数是async函数。)   ask by Rahmani Saif El Moulouk translate from so

Answer 1

The problem is not with fileHash , it's with its caller.(问题不fileHash ，而是它的调用者。)

This(这个) function external() { const foo = await fileHash(...someArgs); } Won't work.(不行) This(这个) async function external() { const foo = await fileHash(...someArgs); } will.(将。) (OTOH, fileHash itself doesn't need to be async to be await ed. You can even await 2 + 2 ).(（OTOH， fileHash本身不需要异步即可await 。您甚至可以await 2 + 2 ）。)