This Question is related to and inspired by How to updoad in old browsers (ex Safari 5.1.4)
Given an <input type="file"> element having a files property containing File objects which inherit from Blob, is it possible to create a ArrayBuffer and convert the ArrayBuffer to a data URI from a Blob or File object without using FileReader?
Approaches have tried so far have been
create a mock WebSocket with .binaryType set to "arraybuffer", create a MessageEvent with event.data set to File object; result is File object at onmessage handler
set prototype of File to ArrayBuffer, Uint8Array; result is Uncaught TypeError: Method ArrayBuffer.prototype.byteLength called on incompatible receiver #<ArrayBuffer>(), Uncaught TypeError: Method get TypedArray.prototype.byteLength called on incompatible receiver [object Object]()
set File at FormData object, attempt to post request body to <iframe>, admittedly not well-conceived; result Bad Request at plnkr
Expected result: Convert Blob and File objects to TypedArray then to data URL, or directly to data URL
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<form method="get" entype="multipart/form-data" target="binaryFrame">
<input id="#avatar" type="file" name="file" />
<input type="submit" />
</form>
<iframe name="binaryFrame"></iframe>
<script>
var input = document.querySelector("input[type=file]");
input.addEventListener("change", handleFiles, true);
// see http://jsfiddle.net/adamboduch/JVfkt/
var sock = new WebSocket("ws://mock");
sock.binaryType = "arraybuffer";
sock.onerror = function(e) {
console.log("sock error", e); // ignore, here
}
sock.onmessage = function(e) {
console.log("socket message", e.data, e.data instanceof ArrayBuffer);
};
function handleFiles(evnet) {
var file = event.target.files[0];
sock.dispatchEvent(new MessageEvent("message", {
data: file
}));
var data = new FormData();
data.append("file", file);
document.forms[0].action = data;
}
</script>
</body>
</html>
See also Display image from blob using javascript and websockets , How can you encode a string to Base64 in JavaScript? ; interestingly ironic as am now asking similar Question https://stackoverflow.com/questions/34302231/is-there-any-way-to-convert-the-file-to-an-arraybuffer-without-filereader-api ; Blob .slice() method , FileReader .readAsDataURL() method
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