Node.js - Download locally docx or pdf encoded as base64 string

Question

I want to store docx or pdf locally inside a folder of my node.js project. Those documents are encoded as Base64 strings but they have specific media type. For this reason when I try to write a file in usual ways, as shown below, the result is something of unreadable.

const express = require("express");
const router = express.Router();
const fs = require('fs');

router.post("/evaluate", function(req, res) {
    var oResume = req.body.resume;
    var sMimeType = oResume.mimeType;
    var sFileExtension = oResume.fileExtension;
    var sBase64 = oResume.content.replace(/(\r\n|\n|\r)/gm, "");

    fs.writeFile("cvs/out."+sFileExtension, sBase64, 'base64', function(err) {
        console.log(err);
      });

    res.status(200).send("OK");
});

How can I store a document which maintain the right format?

Answer 1

I've solved with this solution:

const express = require("express");
const atob = require("atob");
const router = express.Router();
const fs = require('fs');

router.post("/evaluate", function(req, res) {
    var oResume = req.body.resume;
    var sMimeType = oResume.mimeType;
    var sFileExtension = oResume.fileExtension;
    var sBase64 = oResume.content.replace(/(\r\n|\n|\r)/gm, "");
    var sBinaryString = atob(sBase64);
    var len = sBinaryString.length;
    var aBytes = new Uint8Array(len);

    for (var i=0; i<len; i++) {
        aBytes[i] = sBinaryString.charCodeAt(i);
    }
    var blob = Buffer.from(aBytes.buffer);

    fs.writeFile("cvs/out."+sFileExtension, blob, function(err) {
        console.log(err);
     });

    res.status(200).send("OK");
});

module.exports = router;