User:Proteins/followrandomlinkonpage.js

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//<pre>
// Travel to a random page linked in the article (a so-called "aleation" or an "aleatory fugue")
//
// To use this script, add "importScript('User:Proteins/followrandomlinkonpage.js');" to your monobook.js subpage 
// under your user page, as you can see at User:Proteins/monobook.js

function followRandomLinkOnPage() { 
	var alert_string = "";

	var top_node;

	var hyperlinks;
	var num_hyperlinks = 0;

	var random_double = 0.5;
	var random_hyperlink_index = 0;

	var random_link;
	var random_link_href = "";
	var random_link_title = "";

	var num_iterations = 0;
	var max_num_iterations = 100;

	var bad_link = true;

// Get the bodyContent node
	top_node = document.getElementById('bodyContent');
	if (!top_node) { 
		window.alert("There is no bodyContent node in this article.");
		return;
	}
 
// Get a list of the hyperlinks 
	hyperlinks = top_node.getElementsByTagName("A");
	if (!hyperlinks) { 
		window.alert("There are no hyperlinks in this article.");
		return;
	}
	num_hyperlinks = hyperlinks.length;
	if (num_hyperlinks < 1) { 
		window.alert("There are no hyperlinks in this article.");
		return;
	}
 
// Choose a random hyperlink 

	bad_link = true;
	num_iterations = 0;
	random_link = null;
	random_link_href = "";
	random_link_title = "";

	while ((num_iterations<max_num_iterations) && (bad_link)) {
		num_iterations++;

		random_double = num_hyperlinks * Math.random();
		random_hyperlink_index = Math.floor(random_double);
		if ((random_hyperlink_index < 0) || (random_hyperlink_index >= num_hyperlinks)) { continue; }

		random_link = hyperlinks[random_hyperlink_index];
		random_link_href = random_link.href;
		random_link_title = random_link.title;

		if ((!random_link) || (!random_link_title) || (!random_link_title)) {
			// Check that all three exist
			continue;
		} else if (random_link.className) {
			// Don't follow external links
			continue;
		} else if (random_link_title.match(/\(page does not exist\)$/ig)) {
			// Don't follow red links
			continue;
		} else if (random_link_title.match(/^Image:/ig)) {
			// Don't follow Image links
			continue;
		} else if (random_link_title.match(/^Category:/ig)) {
			// Don't follow Category links
			continue;
		} else if (random_link_title.match(/^Special:/ig)) {
			// Don't follow links to Special pages
			continue;
 		} else if ((random_link_title.match(/^Edit\ssection:/i)) && (random_link_href.match(/action\=edit/i))) {
			// Don't follow edit links
			continue;
		}

		if (wgNamespaceNumber == 0) { // special behavior for Main article space
			if (random_link.id) { continue; }
			if (random_link_href.match(/Talk:/ig)) { continue; } 
			if (random_link_href.match(/Wikipedia:/ig)) { continue; } 
			if (random_link_href.match(/Wikipedia talk:/ig)) { continue; } 
			if (random_link_href.match(/Portal:/ig)) { continue; } 
			if (random_link_href.match(/Portal talk:/ig)) { continue; } 
			if (random_link_href.match(/User:/ig)) { continue; } 
			if (random_link_href.match(/User talk:/ig)) { continue; } 
			if (random_link_href.match(/Help:/ig)) { continue; } 
			if (random_link_href.match(/Help talk:/ig)) { continue; } 
			if (random_link_href.match(/Template:/ig)) { continue; } 
			if (random_link_href.match(/Template talk:/ig)) { continue; } 
			if (random_link_href.match(/Category:/ig)) { continue; } 
			if (random_link_href.match(/Category talk:/ig)) { continue; } 
			if (random_link_href.match(/File:/ig)) { continue; } 
			if (random_link_href.match(/File talk:/ig)) { continue; } 
			if (random_link_href.match(/MediaWiki:/ig)) { continue; } 
			if (random_link_href.match(/MediaWiki talk:/ig)) { continue; } 
		} // closes check for Main article space

		bad_link = false;

	} // closes loop generating a random hyperlink

// Follow the randomly chosen link to the new location

	if (bad_link == false) {
		alert_string = "Follow link to the page \"" + random_link_title + "\"\?\n";
		if (window.confirm(alert_string) == true) {
			window.open(random_link_href);
		}
	} else {
		alert_string = "Unable to find a suitable random link in " + max_num_iterations + " attempts.\n";
		window.alert(alert_string);
	}

} // closes function followRandomLinkOnPage()

addOnloadHook(function () {
mw.util.addPortletLink('p-navigation', 'javascript:followRandomLinkOnPage()', 'Follow a lucky link!', 'ca-lucky', 'Follow a randomly chosen link on this page', '@', '');
});
 
//</pre>