From 26c63abe1813cd7cbb603877800e3533ee2beeb0 Mon Sep 17 00:00:00 2001
From: Aman Agrawal <amanagr@zulip.com>
Date: Mon, 22 May 2023 17:26:15 +0000
Subject: [PATCH] overlays: Don't scroll background when modal/overlay is open.

---
 web/src/overlays.ts | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/web/src/overlays.ts b/web/src/overlays.ts
index b5f1053ef0..22a6d8f68f 100644
--- a/web/src/overlays.ts
+++ b/web/src/overlays.ts
@@ -49,6 +49,14 @@ function call_hooks(func_list: Hook[]): void {
     }
 }
 
+export function disable_scrolling(): void {
+    $("html").css({"overflow-y": "hidden"});
+}
+
+function enable_scrolling(): void {
+    $("html").css({"overflow-y": "scroll"});
+}
+
 export function is_active(): boolean {
     return Boolean(open_overlay_name);
 }
@@ -134,6 +142,7 @@ export function open_overlay(opts: OverlayOptions): void {
         },
     };
 
+    disable_scrolling();
     opts.$overlay.addClass("show");
     opts.$overlay.attr("aria-hidden", "false");
     $(".app").attr("aria-hidden", "true");
@@ -240,11 +249,26 @@ export function open_modal(
         }
         close_modal(modal_id);
     });
+
+    function on_show_callback(): void {
+        if (conf.on_show) {
+            conf.on_show();
+        }
+        disable_scrolling();
+    }
+
+    function on_close_callback(): void {
+        if (conf.on_hide) {
+            conf.on_hide();
+        }
+        enable_scrolling();
+    }
+
     Micromodal.show(modal_id, {
         disableFocus: true,
         openClass: "modal--opening",
-        onShow: conf?.on_show,
-        onClose: conf?.on_hide,
+        onShow: on_show_callback,
+        onClose: on_close_callback,
     });
 }
 
@@ -274,6 +298,7 @@ export function close_overlay(name: string): void {
     $("#navbar-fixed-container").attr("aria-hidden", "false");
 
     active_overlay.close_handler();
+    enable_scrolling();
 }
 
 export function close_active(): void {