What you've described is the older Wordpress way of doing it... If you want to use the new uploader in Wordpress 3.5+, you can create a wp.media
object to upload it, similar to the code in wp-admin/js/custom-background.js:
// Create the media frame.
frame = wp.media.frames.customBackground = wp.media({
// Set the title of the modal.
title: $el.data('choose'),
// Tell the modal to show only images.
library: {
type: 'image'
},
// Customize the submit button.
button: {
// Set the text of the button.
text: $el.data('update'),
// Tell the button not to close the modal, since we're
// going to refresh the page when the image is selected.
close: false
}
});
// When an image is selected, run a callback.
frame.on( 'select', function() {
// Grab the selected attachment.
var attachment = frame.state().get('selection').first();
// Run an AJAX request to set the background image.
$.post( ajaxurl, {
action: 'set-background-image',
attachment_id: attachment.id,
size: 'full'
}).done( function() {
// When the request completes, reload the window.
window.location.reload();
});
});
// Finally, open the modal.
frame.open();
the frame.on('select' function(){
code is run when a file is chosen.