Convert image to Base64, dataUrl by Canvas & BLOB | Javscript

Convert image to Base64, dataUrl

function toDataUrl(url, callback) {
    var xhr = new XMLHttpRequest();
    xhr.responseType = 'blob';
    xhr.onload = function () {
        var reader = new FileReader();
        reader.onloadend = function () {
            callback(reader.result);
        }
        reader.readAsDataURL(xhr.response);
    };
    xhr.open('GET', url);
    xhr.send();
}

function toDataUrl(url, callback) {
    var image = new Image();
    image.setAttribute('crossOrigin', 'anonymous');
    image.onload = function () {
        var canvas = document.createElement('canvas');
        canvas.width = this.naturalWidth;
        canvas.height = this.naturalHeight;

        canvas.getContext('2d').drawImage(this, 0, 0, canvas.width, canvas.height);
        callback(canvas.toDataURL('image/png', 1));
    };

    image.src = url;
}