Better HTTP URL validation

js/main.js

@@ -1,9 +1,13 @@
 (function () {
-	// If no source or source is not a URL
+	// If no source
-	if (!urlSearchParams.has('source') || !sourceURL.match(urlRegex))
+	if (!urlSearchParams.has('source'))
-		window.location.replace("index.html");
+		search();
-	insertAddToAltStoreBanner();
+	// If source is not a valid HTTP URL
-})()
+	else if (!isValidHTTPURL(sourceURL)) {
+		alert("Invalid HTTP URL.");
+		search();
+	} else insertAddToAltStoreBanner();
+})();
 
 fetch(sourceURL, {
 	cache: "force-cache"

js/shared.js

@@ -48,18 +48,6 @@ const appHeaderHTML = app => app ? `
 	</div>
 </div>` : undefined;
 
-function formatString(string) {
-	if (!string) return undefined;
-
-	// URLs
-	const urlArray = string.match(urlRegex);
-	const urlSet = [...new Set(urlArray)]; // Converting to set to remove duplicates
-	urlSet.forEach(url => string = string.replaceAll(url, `<a href="${url}">${url}</a>`));
-
-	// New lines
-	return string.replaceAll("\n", "<br>");
-}
-
 function insertAddToAltStoreBanner() {
 	document.getElementById("top")?.insertAdjacentHTML("afterbegin", `
 	<div class="uibanner">
@@ -96,6 +84,30 @@ function insertNavigationBar(title) {
 	setUpBackButton();
 }
 
+// https://stackoverflow.com/a/43467144/19227228
+function isValidHTTPURL(string) {
+	var url;
+	try {
+		url = new URL(string);
+	} catch (error) {
+		console.error("An error occurred.", error);
+		return false;
+	}
+	return url.protocol == "http:" || url.protocol == "https:";
+}
+
+function formatString(string) {
+	if (!string) return undefined;
+
+	// URLs
+	const urlArray = string.match(urlRegex);
+	const urlSet = [...new Set(urlArray)]; // Converting to set to remove duplicates
+	urlSet.forEach(url => string = string.replaceAll(url, `<a href="${url}">${url}</a>`));
+
+	// New lines
+	return string.replaceAll("\n", "<br>");
+}
+
 function setTintColor(color) {
 	document.querySelector(':root')?.style.setProperty("--accent-color", `#${color}`);
 }
@@ -104,6 +116,10 @@ function setUpBackButton() {
 	document.getElementById("back")?.addEventListener("click", () => history.back(1));
 }
 
+function search() {
+	window.location.replace("search.html");
+}
+
 const $ = selector => selector.startsWith("#") && !selector.includes(".") && !selector.includes(" ")
 	? document.getElementById(selector.substring(1))
 	: document.querySelectorAll(selector);