meta-box-image.js

/*
 * Attaches the image uploader to the input field
 */
jQuery(document).ready(function($){

	// Instantiates the variable that holds the media library frame.
	var meta_image_frame;

	// Runs when the image button is clicked.
	$('#meta-image-button').click(function(e){

		// Prevents the default action from occuring.
		e.preventDefault();

		// If the frame already exists, re-open it.
		if ( meta_image_frame ) {
			meta_image_frame.open();
			return;
		}

		// Sets up the media library frame
		meta_image_frame = wp.media.frames.meta_image_frame = wp.media({
			title: meta_image.title,
			button: { text:  meta_image.button },
			library: { type: 'image' }
		});

		// Runs when an image is selected.
		meta_image_frame.on('select', function(){

			// Grabs the attachment selection and creates a JSON representation of the model.
			var media_attachment = meta_image_frame.state().get('selection').first().toJSON();

			// Sends the attachment URL to our custom image input field.
			$('#meta-image').val(media_attachment.url);
		});

		// Opens the media library frame.
		meta_image_frame.open();
	});
});