If I have a big file (e.g. hundreds of MB) does FileReader.readAsArrayBuffer() read the entire file data into an ArrayBuffer?
According to [here[(https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsArrayBuffer) this is what happens.
I have a big .zip file with multiple GB.
I'm concerned of taking the entire RAM when working e.g. on a mobile device.
Is there an alternative approach where a file handle is returned and a portion of the file is read as needed?
You can use Blob.stream() for this:
const bigBlob = new Blob(["somedata".repeat(10e5)]);
console.log("Will read a %sbytes Blob", bigBlob.size)
const reader = bigBlob.stream().getReader();
let chunks = 0;
reader.read().then(function processChunk({ done, value }) {
if (done) {
console.log("Stream complete. Read in %s chunks", chunks);
return;
}
// do whatever with the chunk
// 'value' is an ArrayBuffer here
chunks++;
return reader.read().then(processChunk);
}).catch(console.error);