Modified "tumblr welcome page" script to hide a custom interstitial rather than redirecting to a custom page.

snippet.js

/**
 * Tumblr Welcome Page
 *
 * This JS snippet should be installed in your Tumblr theme.
 * Every new browser session, this will hide the custom interstitial
 * if the user has already seen it once.
 */

$(document).ready( function() {
	
	function atBaseUrl() {
		return window.location.pathname == "/";
	}
	
	// source: https://mathiasbynens.be/notes/localstorage-pattern
	var hasStorage = (function() {
		try {
			sessionStorage.setItem('mod', 'mod');
			sessionStorage.removeItem('mod');
			return true;
		} catch (exception) {
			return false;
		}
	}());

	// make sure we support sessionStorage, otherwise do nothing
	if (hasStorage) {
	
		// make sure we're at the root of the current page, otherwise do nothing
		if (atBaseUrl()) {
	
			// if we don't have the sessionStorage entry, create it
			if (sessionStorage.getItem('visited') === null) {
				sessionStorage.setItem('visited', 'true');
			} else {
				// otherwise, we've already been here - hide the interstitial immediately
				$('header.cover').hide();
				$('.holder').addClass('visible');
			}
	
		}
	
	}
});