diff --git a/docs/plugins/browser-check.md b/docs/plugins/browser-check.md
index 882f0eeb..6f67d088 100644
--- a/docs/plugins/browser-check.md
+++ b/docs/plugins/browser-check.md
@@ -96,7 +96,7 @@ As with all simulated plugins, you can override the default (actual) data with f
         var trial = {
           type: jsPsychBrowserCheck,
           inclusion_function: (data) => {
-            return ['chrome', 'firefox'].contains(data.browser);
+            return ['chrome', 'firefox'].includes(data.browser);
           },
           exclusion_message: `<p>You must use Chrome or Firefox to complete this experiment.</p>`
         };
@@ -149,4 +149,4 @@ As with all simulated plugins, you can override the default (actual) data with f
           <iframe src="../../demos/jspsych-browser-check-demo4.html" width="90%;" height="500px;" frameBorder="0"></iframe>
         </div>
 
-    <a target="_blank" rel="noopener noreferrer" href="../../demos/jspsych-browser-check-demo4.html">Open demo in new tab</a>
\ No newline at end of file
+    <a target="_blank" rel="noopener noreferrer" href="../../demos/jspsych-browser-check-demo4.html">Open demo in new tab</a>