Note: After saving, you have to bypass your browser's cache to see the changes. Internet Explorer: press Ctrl-F5, Mozilla: hold down Shift while clicking Reload (or press Ctrl-Shift-R), Opera/Konqueror: press F5, Safari: hold down Shift + Alt while clicking Reload, Chrome: hold down Shift while clicking Reload.
if (mw.config.get('wgNamespaceNumber')==6) {
	var articleId = mw.config.get( 'wgArticleId' );
	if (articleId > "0") {
		mid = "M" + articleId;
		$('#firstHeading')
			.append( $("<a />")
				.text(mid)
				.attr("href", "https://commons.wikimedia.org/entity/" + mid)
				.css({
					"margin-left": "1em",
					"font-size": "60%"
				})
			);
		$('#firstHeading')
			.append( $("<a />")
				.text("(ttl)")
				.attr("href", "https://commons.wikimedia.org/entity/" + mid + ".ttl")
				.css({
					"margin-left": "0.5em",
					"font-size": "60%"
				})
			);
		$('#firstHeading')
			.append( $("<a />")
				.text("(json)")
				.attr("href", "https://commons.wikimedia.org/entity/" + mid + ".json")
				.css({
					"margin-left": "0.5em",
					"font-size": "60%"
				})
			);
	}
}