Upload images to a Node.JS server without using <form>

Question

I have a node.js server, which uses express-fileupload to accept images. Now I'm working on the function to upload an image. But I don't want to use < form > since I prefer xhtml request for various reasons, but mainly because I don't want to redirect the user, after he uploads an image.

I have tried reading the picture as dataURI, sending it to the server, decoding it and writing it to a file, which didnt work and seemed to resource intensive and laborious.

//I used the dataString from the callback method and wrote it to a file using fs.writeFile
function dataURItoimage(dataString, callback){
   const atob = require("atob");

   dataString.replace("data:image/jpeg;base64,", "");
   dataString.replace("data:image/png;base64,", "");

   atob(dataString);
   callback(null, dataString);
}

//User side code
avatarInput.addEventListener("change", (e) => {
    const reader = new FileReader();
    reader.readAsDataURL(avatarInput.files[0]);
    reader.onload = () => {
        avatar = reader.result;
        tosend.avatar = reader.result;
    }
}, false);

uploadButton.onclick = () => {
    var request = new XMLHttpRequest();
    request.open("POST", "/avatarUpload");
    request.setRequestHeader("Content-Type", "application/json");

    var tosend = {avatar: ""};
    tosend.avatar = avatar;

    request.send(JSON.stringify(tosend));
}

Is there a better way to upload an image, which the user can select, to a node.js server?

Answer 1

So I did it this way:

    var request = new XMLHttpRequest();
    request.open("POST", "/test");

    var fd = new FormData();
    fd.append("file", avatarInput.files[0]);
    request.send(fd);

I created a FormData Object, appended the image, which the user chose in an input called "avatarInput", and send the object to the server. On server side I used express-fileupload to access the file:

app.post("/test", (req, res) => {
    if(req.files){
        //With the follwing command you can save the recieved image
        req.files.file.mv("./file.png",  (err) => {if(err)throw err});
    }
    res.end();
});

Answer 2

You can try this example. It worked for me. I hope it can help you.

Sending dataURL throw Ajax request:

const dataURL = snapshotCanvas.toDataURL('image/png');
$.ajax({
    url: 'http://localhost:3000/upload-image',
    dataType: 'json',
    data: { data: dataURL },
    type: 'POST',
    success: function(data) {}
});

Receiving request:

router.post('/', (req, res) => {
    const base64 = req.body.data.replace(/^data:image\/png;base64,/, "");
    fs.writeFileSync(`uploads/images/newImage.jpg`, base64, {encoding: 'base64'});
}