Can anyone think of a faster or more correct way to convert a canvas object to a blob?

dataURIToBlob.js

function dataURIToBlob(dataURI) {
    var parts = dataURI.split(',');
    var binary = atob(parts[1]);
    var type = parts[0];
    var array = [];
    for(var i = 0; i < binary.length; i++) {
        array.push(binary.charCodeAt(i));
    }
    return new Blob([new Uint8Array(array).buffer], {type: type});
}