upload.js

// Image upload handler
$('#upload').change(function () {
    const file = this.files[0];

    const reader = new FileReader();
    reader.readAsDataURL(file);

    reader.onload = function () {
        $('body').css('background-image', 'url("' + reader.result + '")');
        $('#colors').html('<h2>Processing...</h2>');

        getColors(reader.result.substr(reader.result.search('base64,') + 7));
    };

    reader.onerror = function (error) {
        console.error('Error: ', error);
    };

});