diff --git a/Web-Browsers.md b/Web-Browsers.md
index 2dc59dd..b1a357f 100644
--- a/Web-Browsers.md
+++ b/Web-Browsers.md
@@ -20,3 +20,10 @@ If you want to embed your game into your web page, using iframe is strongly reco
 # Restrictions
 
 On both Android and iOS, touching is required to start sound. This is the browser's restriction.
+
+# Emulate context-lost
+
+`document.getElementsByTagName("canvas")[0].getContext("webgl").getExtension('WEBGL_lose_context').loseContext()
+undefined`
+
+Note that Ebiten automatically restores images when the context is lost.