Error: await is only valid in async function when function is already within an async function

问题

Goal: Get a list of files from my directory; get the SHA256 for each of those files

Error: await is only valid in async function

I'm not sure why that is the case since my function is already wrapped inside an async function.. any help is appreciated!

const hasha = require('hasha');

const getFiles = () => {
    fs.readdir('PATH_TO_FILE', (err, files) => {
        files.forEach(i => {
           return i;
        });
    });   
}
(async () => {
    const getAllFiles = getFiles()
    getAllFiles.forEach( i => {
        const hash = await hasha.fromFile(i, {algorithm: 'sha256'});
        return console.log(hash);
    })
});

回答1:

Your await isn't inside an async function because it's inside the .forEach() callback which is not declared async.

You really need to rethink how you approach this because getFiles() isn't even returning anything. Keep in mind that returning from a callback just returns from that callback, not from the parent function.

Here's what I would suggest:

const fsp = require('fs').promises;
const hasha = require('hasha');

async function getAllFiles() {
    let files = await fsp.readdir('PATH_TO_FILE');
    for (let file of files) {
        const hash = await hasha.fromFile(i, {algorithm: 'sha256'});
        console.log(hash);            
    }
}

getAllFiles().then(() => {
    console.log("all done");
}).catch(err => {
    console.log(err);
});

In this new implementation:

Use const fsp = require('fs').promises to get the promises interface for the fs module.
Use await fsp.readdir() to read the files using promises
Use a for/of loop so we can properly sequence our asynchronous operations with await.
Call the function and monitor both completion and error.

来源：https://stackoverflow.com/questions/60878086/error-await-is-only-valid-in-async-function-when-function-is-already-within-an

标签

node.js

asynchronous

sha256