JavaScript Binary Data Converting between Blobs and ArrayBuffers
Example
JavaScript has two primary ways to represent binary data in the browser. ArrayBuffers/TypedArrays contain mutable (though still fixed-length) binary data which you can directly manipulate. Blobs contain immutable binary data which can only be accessed through the asynchronous File interface.
Convert a Blob to an ArrayBuffer (asynchronous)
var blob = new Blob(["\x01\x02\x03\x04"]),
fileReader = new FileReader(),
array;
fileReader.onload = function() {
array = this.result;
console.log("Array contains", array.byteLength, "bytes.");
};
fileReader.readAsArrayBuffer(blob);
6
Convert a
Convert a Blob to an ArrayBuffer using a Promise (asynchronous)
var blob = new Blob(["\x01\x02\x03\x04"]);
var arrayPromise = new Promise(function(resolve) {
var reader = new FileReader();
reader.onloadend = function() {
resolve(reader.result);
};
reader.readAsArrayBuffer(blob);
});
arrayPromise.then(function(array) {
console.log("Array contains", array.byteLength, "bytes.");
});
Convert an ArrayBuffer or typed array to a Blob
var array = new Uint8Array([0x04, 0x06, 0x07, 0x08]);
var blob = new Blob([array]);
