image preview via JS

function previewImage(file) {
    var reader = new FileReader();
    reader.onload = function (e) {
        
        var o = $('<img class="img">').attr('src', e.target.result),
            r = $('.img-box');
        
        o.load(function (e) {
            r.append(o);
            var h = o.height(),
                w = o.width();
            if (w > h && w > 100)
                o.width(100);
            else if (h > w && h > 100)
                o.height(100);
        });
        
    };
    reader.readAsDataURL(file.files[0]);
}​