How can javascript upload a blob?

AJAX and XMLHttpRequest Alternatives

The Fetch API is great, but let's explore the traditional AJAX methods such as jQuery’s $.ajax and XMLHttpRequest (XHR):

The jQuery Way

Utilizing jQuery’s $.ajax method, remember to set processData and contentType to false. This prevents pre-processing and sets the right MIME type:

// Prepare your package (Blob data), address it (FormData), and ready for shipping
const formData = new FormData();
formData.append('file', blob, 'filename');

$.ajax({
    url: 'YOUR_ENDPOINT', // Don't send it to Santa, put your endpoint here
    type: 'POST',
    data: formData,
    processData: false, // jQuery, hands off my data!
    contentType: false, // We'll handle the MIME type, thanks jQuery
    success: function(data) {
        console.log('Success! Blob uploaded:', data);
    },
    error: function(err) {
        console.error('Oops! Postman tripped over:', err); // Even Postmen have bad days...
    }
});
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Plain Ol’ XMLHttpRequest

Or, for a true OG path of XMLHttpRequest, take advantage of upload progress events:

// Prepare your package (Blob data), address it (FormData), and ready for shipping
const formData = new FormData();
formData.append('file', blob, 'filename');
// Time for our trusty carrier pigeon... err XMLHttpRequest
const xhr = new XMLHttpRequest();

// At the post office now
xhr.open('POST', 'YOUR_ENDPOINT', true);

xhr.upload.onprogress = function(e) {
    // Our pigeon is taking its sweet time, but you can track it!
    if (e.lengthComputable) {
        console.log('Upload progress:', (e.loaded / e.total) * 100, '%');
    }
};

xhr.onload = function() {
    if (this.status == 200) {
        console.log('Success! Blob uploaded:', JSON.parse(this.response));
    }
    else {
      console.error('The pigeon failed to deliver the package!')
    }
};

xhr.send(formData); // Fly, Pigeon, fly!


Handling Data Types: Image, Audio, Files

Different data types require different handling. Whether it’s audio, images, or general files, here's how to manage diverse Blobs:

Audio Recording: Mic Check, 1, 2

Using getUserMedia() in modern browsers and Recorder.js for sound processing, audio capture and uploading is a breeze:

navigator.mediaDevices.getUserMedia({ audio: true })
.then(stream => {
    // Recorder.js does the heavy lifting
});


Image Uploading: Say Cheese!

For images, take advantage of Canvas API to turn images into a Blob and upload. Don't forget to smile:

canvas.toBlob(function(blob) {
    const formData = new FormData();
    formData.append('file', blob, 'say_cheese.png'); // "Cheese!
    // Call fetch or XHR to send formData
}, 'image/png');


FileReader Perks: Peek before Sending

Ever wanted to peek at the blob data before sending? Welcome to the FileReader club:

const reader = new FileReader();
reader.onloadend = function() {
    // Shhh! We're reading a Blob diary here
};
reader.readAsDataURL(blob);


Server-side Scripts

Back-end, specifically PHP, handles the uploaded Blob like a regular file:

<?php
// If Santa (server) got your package ("file")
if (isset($_FILES["file"])) {
    // Santa delivers it to the right destination
    move_uploaded_file($_FILES["file"]["tmp_name"], "upload/" . $_FILES["file"]["name"]);
}
?>
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Checking Browser Compatibility

Make sure the compatibility list includes your target browser before you choose an upload method. While Fetch API has broad support, older browsers may require XMLHttpRequest fallbacks or polyfills (because everyone appreciates backward-compatible good ol' times).

Mistakes to Avoid

When creating upload functionality, note the following common pitfalls to prevent frustration:

Asynchronous operations

You're dealing with async operations, so handle responses correctly to prevent blocking UI updates.

Error Handling

Implement robust error checking for both client and server-side scripts - Murphy's Law is always on the prowl.

Security Concerns

Review uploaded files carefully on the server-side and scrub out potentially harmful files - Because even Blobs can have a dark side!

File Size Limitations

Check and manage file size limits on both client and server-side to prevent unwelcome surprises.

Beyond Basic Blob Upload: FileReader, Filenames and Testing

Working with Blobs goes beyond mere uploading. Here are some extra toppings on your Blob pizza:

Naming a Blob

To assign a filename to your Blob on the server, include it when you append the Blob to FormData:

// Name that Blob!
formData.append('file', blob, 'desiredFilename.ext');
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Testing! Testing!

Always test your solution across relevant browsers and devices. Ensures your website doesn’t deny any users the fun of ablazing Blob extravaganza!