如何使用nodejs推入数组

Question

I am trying to push the file into the array named FileName however when I try to console.log(FileName) all I get is the empty array! Any input would be greatly appreciated!

const fs = require("fs");
const mm = require("music-metadata");
const dataFolder = "../../Songs";
const util = require("util");
//requiring path and fs modules
const path = require("path");
let FileName = [];
fs.readdir(dataFolder, (err, files) => {
  files.forEach(e => {
    return mm.parseFile(`../../Songs/${e}`).then(metadata => {
      // console.log(`../..Songs/${e}`);
      FileName.push(e);
      // console.log(
      //   util.inspect(metadata.common.title, {
      //     showHidden: false,
      //     depth: null
      //   })
      // );
    });
  });
});
console.log(FileName);
// mm.parseFile(
//   "/Users/nathangriffith/Desktop/dashboard/Songs/04 Smoke and Mirrors.m4a"
// )
//   .then(metadata => {
//     console.log(
//       metadata.native.iTunes[0].value
//     );
//   })
//   .catch(err => {
//     console.error(err.message);
//   });

Answer 1

Assuming that you need metadata in your FileName array:

const files = readdirSync(dataFolder); // Now files is an array of file names

Promise
  .all(files.map(file => mm.parseFile(`../../Songs/${file}`)
  .then(metadataArr => {
    console.log(metadataArr); // This should be your parsed metdatas
  });

Answer 2

You are running an async function and expecting it to complete before the next line (console.log) runs. The log runs during the runtime of readdir, and therefore prints the value of FileName as it is before readdir changes it.

You can either change the program to use await/async correctly, or implement readdirSync instead.