Broke out shared code into functions.js

contentScript.js

 		}
 	}
 	if (!killSticky) return;
-	
-	console.log("Killing all stickies!");
-	document.querySelectorAll('body *').forEach(element => {
-		if (getComputedStyle(element).position === 'fixed' || 
-			getComputedStyle(element).position === 'sticky') {
-			element.remove();
-		}
-	});
-}
+	killSticky();
+}

functions.js

+/*******************************/
+/* EVENT LISTENER MANIPULATION */
+/*******************************/
+
+/*	Adds an event listener to a button (or other clickable element), attaching 
+	it to both "click" and "keyup" events (for use with keyboard navigation).
+	Optionally also attaches the listener to the 'mousedown' event, making the 
+	element activate on mouse down instead of mouse up. */
+Element.prototype.addActivateEvent = function(func, includeMouseDown) {
+	let ael = this.activateEventListener = (event) => { if (event.button === 0 || event.key === ' ') func(event) };
+	if (includeMouseDown) this.addEventListener("mousedown", ael);
+	this.addEventListener("click", ael);
+	this.addEventListener("keyup", ael);
+}
+
+/*	Removes event listener from a clickable element, automatically detaching it
+	from all relevant event types. */
+Element.prototype.removeActivateEvent = function() {
+	let ael = this.activateEventListener;
+	this.removeEventListener("mousedown", ael);
+	this.removeEventListener("click", ael);
+	this.removeEventListener("keyup", ael);
+}
+
+/***********/
+/* HELPERS */
+/***********/
+
+function killSticky() {
+	console.log("Killing all stickies!");
+	document.querySelectorAll('body *').forEach(element => {
+		if (getComputedStyle(element).position === 'fixed' || 
+			getComputedStyle(element).position === 'sticky') {
+			element.remove();
+		}
+	});
+}
+
+String.prototype.hasPrefix = function (prefix) {
+	return (this.lastIndexOf(prefix, 0) === 0);
+}

options.html

 	</div>
 	<p>NOTE: Exclusion patterns override matching patterns; if a page is <em>both</em> matched <em>and</em> excluded, stickies will <strong>not</strong> be killed on that page.</p>
 </body>
+<script src="functions.js"></script>
 <script src="options.js"></script>
 </html>

options.js

-/*******************************/
-/* EVENT LISTENER MANIPULATION */
-/*******************************/
-
-/*	Adds an event listener to a button (or other clickable element), attaching 
-	it to both "click" and "keyup" events (for use with keyboard navigation).
-	Optionally also attaches the listener to the 'mousedown' event, making the 
-	element activate on mouse down instead of mouse up. */
-Element.prototype.addActivateEvent = function(func, includeMouseDown) {
-	let ael = this.activateEventListener = (event) => { if (event.button === 0 || event.key === ' ') func(event) };
-	if (includeMouseDown) this.addEventListener("mousedown", ael);
-	this.addEventListener("click", ael);
-	this.addEventListener("keyup", ael);
-}
-
-/*	Removes event listener from a clickable element, automatically detaching it
-	from all relevant event types. */
-Element.prototype.removeActivateEvent = function() {
-	let ael = this.activateEventListener;
-	this.removeEventListener("mousedown", ael);
-	this.removeEventListener("click", ael);
-	this.removeEventListener("keyup", ael);
-}
-
 /*******************/
 /* EVENT LISTENERS */
 /*******************/