Autolink URLs in messages

src/js/basic.js

@@ -19,12 +19,12 @@ const qa = s => document.querySelectorAll(s);
  */
 class ElemJS {
 	constructor(type) {
-		if (type instanceof HTMLElement) {
+		if (typeof type === "string") {
-			// If passed an existing element, bind to it
+			// Passed a tag name; create an element to bind to
-			this.bind(type);
-		} else {
-			// Otherwise, create a new detached element to bind to
 			this.bind(document.createElement(type));
+		} else {
+			// Passed an existing element; bind to it
+			this.bind(type);
 		}
 		this.children = [];
 	}

src/js/events/message.js

@@ -68,9 +68,7 @@ function cleanHTML(html) {
 }
 
 // Here we put all the processing of the messages that isn't as likely to potentially lead to security issues
-function postProcessElements(rootNode) {
+function postProcessElements(element) {
-	const element = rootNode.element
-
 	element.querySelectorAll("pre").forEach(n => {
 		new HighlightedCode(n)
 	})
@@ -95,13 +93,11 @@ class HTMLMessage extends MatrixEvent {
 		this.clearChildren()
 
 		let html = this.data.content.formatted_body
-		const content = ejs("div")
 
 		const fragment = cleanHTML(html)
-		content.element.appendChild(fragment)
+		postProcessElements(fragment)
-		postProcessElements(content)
 
-		this.child(content)
+		this.child(ejs(fragment))
 
 		super.render()
 	}
@@ -121,10 +117,33 @@ class HTMLMessage extends MatrixEvent {
 	}
 }
 
+function autoLinkText(text) {
+	const fragment = ejs(new DocumentFragment())
+	let lastIndex = 0
+	text.replace(/https?:\/\/(?:[A-Za-z-]+\.)+[A-Za-z]{1,10}(?::[0-9]{1,6})?(?:\/[^ ]*)?/g, (url, index) => {
+		// add text before URL
+		fragment.addText(text.slice(lastIndex, index))
+		// add URL
+		fragment.child(
+			ejs("a")
+				.attribute("target", "_blank")
+				.attribute("noopener", "")
+				.attribute("href", url)
+				.addText(url)
+		)
+		// update state
+		lastIndex = index + url.length
+	})
+	// add final text
+	fragment.addText(text.slice(lastIndex))
+	return fragment
+}
+
 class TextMessage extends MatrixEvent {
 	render() {
 		this.clearChildren()
-		this.text(this.data.content.body)
+		const fragment = autoLinkText(this.data.content.body)
+		this.child(fragment)
 		super.render()
 	}
 

src/sass/components/messages.sass

@@ -49,6 +49,7 @@
   overflow-wrap: anywhere
   opacity: 1
   transition: opacity 0.2s ease-out
+  white-space: pre-wrap
 
   &--pending
     opacity: 0.5