diff --git a/chrome/content/zotero/runJS.html b/chrome/content/zotero/runJS.html
index 622fad48b3..f79199f74f 100644
--- a/chrome/content/zotero/runJS.html
+++ b/chrome/content/zotero/runJS.html
@@ -10,12 +10,20 @@
 		
 		<main>
 			<div class="textbox-container">
-				<label for="code">Code:</label>
+				<div class="textbox-header">
+					<label class="textbox-label" for="code">Code:</label>
+					<label id="run-as-async-label" for="run-as-async">
+						<input id="run-as-async" type="checkbox" onclick="update()">
+						Run as async function
+					</label>
+				</div>
 				<textarea id="code"></textarea>
 			</div>
 			
 			<div class="textbox-container">
-				<label for="result">Result:</label>
+				<div class="textbox-header">
+					<label id="result-label" class="textbox-label" for="result"/>
+				</div>
 				<textarea id="result" readonly></textarea>
 			</div>
 		</main>
diff --git a/chrome/content/zotero/runJS.js b/chrome/content/zotero/runJS.js
index 5662db308d..780656c2f0 100644
--- a/chrome/content/zotero/runJS.js
+++ b/chrome/content/zotero/runJS.js
@@ -1,11 +1,35 @@
-function run() {
+function update() {
+	var isAsync = document.getElementById('run-as-async').checked;
+	var resultLabel = document.getElementById('result-label');
+	var val = isAsync ? 'Return value' : 'Result';
+	resultLabel.textContent = val + ':';
+}
+
+async function run() {
 	var win = Zotero.getMainWindow();
 	if (!win) {
 		return;
 	}
 	var code = document.getElementById('code').value;
-	var result = win.eval(code);
-	document.getElementById('result').value = Zotero.Utilities.varDump(result);
+	var isAsync = document.getElementById('run-as-async').checked;
+	var result;
+	var resultTextbox = document.getElementById('result');
+	try {
+		if (isAsync) {
+			code = '(async function () {' + code + '})()';
+			result = await win.eval(code);
+		}
+		else {
+			result = win.eval(code);
+		}
+	}
+	catch (e) {
+		resultTextbox.classList.add('error');
+		resultTextbox.value = e;
+		return;
+	}
+	resultTextbox.classList.remove('error');
+	resultTextbox.value = Zotero.Utilities.varDump(result);
 }
 
 window.addEventListener('keypress', function (event) {
@@ -30,3 +54,5 @@ window.addEventListener('keypress', function (event) {
 
 var shortcut = Zotero.isMac ? 'Cmd-R' : 'Ctrl+R';
 document.getElementById('run-label').textContent = `(${shortcut})`;
+
+update();
diff --git a/chrome/skin/default/zotero/runJS.css b/chrome/skin/default/zotero/runJS.css
index 69029a0147..8fc6b41f4c 100644
--- a/chrome/skin/default/zotero/runJS.css
+++ b/chrome/skin/default/zotero/runJS.css
@@ -29,18 +29,41 @@ main {
 	flex-direction: column;
 	align-items: stretch;
 	flex-grow: 1;
-	font-size: 14px;
 	padding: 10px;
 }
 
+.textbox-header {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	line-height: 1.5;
+}
+
+.textbox-label {
+	font-size: 15px;
+}
+
+#run-as-async-label {
+	font-size: 13px;
+}
+
 label {
 	flex-grow: 0;
 }
 
+input[type=checkbox] {
+	margin-top: 0;
+	margin-bottom: 0;
+}
+
 textarea {
 	flex-grow: 1;
 	margin: 5px 0;
 	font-family: Monaco, Consolas, Inconsolata, monospace;
 	font-size: 12px;
 	resize: none;
+}
+
+textarea.error {
+	color: red;
 }
\ No newline at end of file