WordPress sponsors plugin with custom featured image meta box for banners.

admin.js

jQuery( document ).ready( function( $ ) {
	// Image
	// @see https://github.com/WordPress/WordPress/blob/4.1/wp-includes/js/media-editor.js#L721-L739
	$( '.pronamic-image-control' ).on( 'click', '.set-post-image', function( event ) {
		event.preventDefault();

		var $imageControl = $( event.delegateTarget );

		var config = $imageControl.data( 'image-control' );

		var frame  = $imageControl.data( 'frame' );

		// If the media frame already exists, reopen it.
		if ( frame ) {
			frame.open();
			return;
		}

		// Create the media frame.
		frame = wp.media( {
			// Set the title of the modal.
			title: config.labels.select,
			// Tell the modal to show only images.
			library: {
				type: config.mime_type,
			},
			// Customize the submit button.
			button: {
				// Set the text of the button.
				text: config.labels.select,
				// Tell the button not to close the modal, since we're
				// going to refresh the page when the image is selected.
				close: false
			}
		} );

		$imageControl.data( 'frame', frame );

		// When an image is selected, run a callback.
		frame.on( 'select', function() {
			var settings = wp.media.view.settings;

			// Grab the selected attachment.
			var attachment = frame.state().get( 'selection' ).first();

			// Run an AJAX request to set the background image.
			config.image_id = attachment.id;

			wp.media.post( 'pronamic_set_image', config ).done( function( html ) {
				$imageControl.html( html );

				frame.close();
			});
		} );
		// Finally, open the modal.
		frame.open();
	} ).on( 'click', '.remove-post-image', function( event ) {
		event.preventDefault();

		var $imageControl = $( event.delegateTarget );

		var config = $imageControl.data( 'image-control' );

		config.image_id = false;

		wp.media.post( 'pronamic_set_image', config ).done( function( html ) {
			$imageControl.html( html );
		} );
	} );
} );