diff --git a/Changes.md b/Changes.md
index f4ea7cb42..e6d964310 100644
--- a/Changes.md
+++ b/Changes.md
@@ -84,15 +84,17 @@ Unreleased
 - BREAKING: ppx: print the `deprecated` alert for `@@deriving abstract` at the
   declaration site rather than at (all) usages
   ([#1269](https://github.com/melange-re/melange/pull/1269))
-- core: prettify melange code generation for `for` loops
+- JS generation: prettify `for` loops
   ([#1275](https://github.com/melange-re/melange/pull/1275))
-- core: improve generated code formatting for `throw` and `return` statements,
-  JS objects ([#1286](https://github.com/melange-re/melange/pull/1286),
+- JS generation: improve formatting for `throw` and `return` statements, JS
+  objects ([#1286](https://github.com/melange-re/melange/pull/1286),
   [#1289](https://github.com/melange-re/melange/pull/1289))
-- core: improve generated code formatting for empty return and continue
-  statements ([#1288](https://github.com/melange-re/melange/pull/1288))
-- core: in generated code, remove trailing spaces before commas in `export`
+- JS generation: improve formatting for empty return and continue statements
+  ([#1288](https://github.com/melange-re/melange/pull/1288))
+- JS generation: remove trailing spaces before commas in `export`
   ([#1287](https://github.com/melange-re/melange/pull/1287))
+- JS generation: remove redundant switch cases branches
+  ([#1295](https://github.com/melange-re/melange/pull/1295))
 
 4.0.1 2024-06-07
 ---------------
diff --git a/jscomp/core/lam_compile.ml b/jscomp/core/lam_compile.ml
index ecd08f14e..4e90c96c6 100644
--- a/jscomp/core/lam_compile.ml
+++ b/jscomp/core/lam_compile.ml
@@ -598,6 +598,15 @@ and compile_general_cases :
              break still should not be printed (it will be continuned)
          TOOD: disabled temporarily since it's not perfect yet *)
       morph_declare_to_assign cxt (fun cxt declaration ->
+          (* Exclude cases that are the same as the default if the default is defined *)
+          let cases =
+            match default with
+            | Default lam ->
+                List.filter
+                  ~f:(fun (_, lam1) -> not (Lam.eq_approx lam lam1))
+                  cases
+            | _ -> cases
+          in
           let default =
             match default with
             | Complete -> None
diff --git a/jscomp/test/dist/jscomp/test/flow_parser_reg_test.js b/jscomp/test/dist/jscomp/test/flow_parser_reg_test.js
index 29b4af314..0f1e83227 100644
--- a/jscomp/test/dist/jscomp/test/flow_parser_reg_test.js
+++ b/jscomp/test/dist/jscomp/test/flow_parser_reg_test.js
@@ -2167,8 +2167,6 @@ function parse_sign(f) {
   switch (match.hd) {
     case 43 :
         return eat(f);
-    case 44 :
-        return f;
     case 45 :
         const init = eat(f);
         return {
diff --git a/jscomp/test/dist/jscomp/test/gpr_1438.js b/jscomp/test/dist/jscomp/test/gpr_1438.js
index 7ca2a85ac..3d4a12f6d 100644
--- a/jscomp/test/dist/jscomp/test/gpr_1438.js
+++ b/jscomp/test/dist/jscomp/test/gpr_1438.js
@@ -12,22 +12,6 @@ function actionKey(key, a, b, c, d, e) {
         return e;
     case 116 :
         return b;
-    case 100 :
-    case 101 :
-    case 102 :
-    case 103 :
-    case 104 :
-    case 105 :
-    case 108 :
-    case 109 :
-    case 110 :
-    case 111 :
-    case 112 :
-    case 113 :
-    case 114 :
-    case 115 :
-    case 117 :
-        break;
     case 99 :
     case 118 :
         return a;
diff --git a/jscomp/test/dist/jscomp/test/gpr_1698_test.js b/jscomp/test/dist/jscomp/test/gpr_1698_test.js
index 0622d9535..157e8ef7e 100644
--- a/jscomp/test/dist/jscomp/test/gpr_1698_test.js
+++ b/jscomp/test/dist/jscomp/test/gpr_1698_test.js
@@ -167,8 +167,6 @@ function compare(context, state, _a, _b) {
           switch (b.TAG) {
             case /* Pow */ 3 :
                 return 1;
-            case /* Gcd */ 5 :
-                return -1;
             default:
               return -1;
           }
diff --git a/jscomp/test/dist/jscomp/test/mario_game.js b/jscomp/test/dist/jscomp/test/mario_game.js
index 0e052ac2e..c165a0d09 100644
--- a/jscomp/test/dist/jscomp/test/mario_game.js
+++ b/jscomp/test/dist/jscomp/test/mario_game.js
@@ -2363,25 +2363,6 @@ function keydown(evt) {
       case 83 :
           pressed_keys.down = true;
           break;
-      case 67 :
-      case 69 :
-      case 70 :
-      case 71 :
-      case 72 :
-      case 73 :
-      case 74 :
-      case 75 :
-      case 76 :
-      case 77 :
-      case 78 :
-      case 79 :
-      case 80 :
-      case 81 :
-      case 82 :
-      case 84 :
-      case 85 :
-      case 86 :
-          break;
       case 87 :
           pressed_keys.up = true;
           break;
diff --git a/jscomp/test/dist/jscomp/test/ocaml_re_test.js b/jscomp/test/dist/jscomp/test/ocaml_re_test.js
index 8bddb9d38..e6af06aae 100644
--- a/jscomp/test/dist/jscomp/test/ocaml_re_test.js
+++ b/jscomp/test/dist/jscomp/test/ocaml_re_test.js
@@ -3508,23 +3508,6 @@ function parse(multiline, dollar_endonly, dotall, ungreedy, s) {
                 });
         case 90 :
             return /* Last_end_of_line */ 7;
-        case 58 :
-        case 59 :
-        case 60 :
-        case 61 :
-        case 62 :
-        case 63 :
-        case 64 :
-        case 91 :
-        case 92 :
-        case 93 :
-        case 94 :
-        case 95 :
-        case 96 :
-            return {
-              TAG: /* Set */ 0,
-              _0: single(c)
-            };
         case 98 :
             return alt$1({
                   hd: /* Beg_of_word */ 2,
diff --git a/jscomp/test/dist/jscomp/test/ocaml_typedtree_test.js b/jscomp/test/dist/jscomp/test/ocaml_typedtree_test.js
index 919971832..4225b8498 100644
--- a/jscomp/test/dist/jscomp/test/ocaml_typedtree_test.js
+++ b/jscomp/test/dist/jscomp/test/ocaml_typedtree_test.js
@@ -66087,8 +66087,6 @@ function is_nonexpansive_mod(_mexp) {
                       return false;
                   case /* Tstr_include */ 12 :
                       return is_nonexpansive_mod(id_mod_list._0.incl_mod);
-                  case /* Tstr_attribute */ 13 :
-                      return true;
                   default:
                     return true;
                 }
diff --git a/jscomp/test/dist/jscomp/test/string_test.js b/jscomp/test/dist/jscomp/test/string_test.js
index 1ebf0338f..c770f13d1 100644
--- a/jscomp/test/dist/jscomp/test/string_test.js
+++ b/jscomp/test/dist/jscomp/test/string_test.js
@@ -47,11 +47,6 @@ function gg(x) {
     case 4 :
         a = 6;
         break;
-    case 5 :
-    case 6 :
-    case 7 :
-        a = 8;
-        break;
     case 8 :
         a = 7;
         break;
diff --git a/jscomp/test/dist/jscomp/test/tscanf_test.js b/jscomp/test/dist/jscomp/test/tscanf_test.js
index 2a707dd3b..35d0a5647 100644
--- a/jscomp/test/dist/jscomp/test/tscanf_test.js
+++ b/jscomp/test/dist/jscomp/test/tscanf_test.js
@@ -2018,11 +2018,6 @@ function scan_elems$3(ib, accu) {
                     hd: i,
                     tl: accu
                   });
-          case "]" :
-              return Stdlib__List.rev({
-                    hd: i,
-                    tl: accu
-                  });
           default:
             return Stdlib__List.rev({
                   hd: i,
diff --git a/jscomp/test/dist/jscomp/test/typeof_test.js b/jscomp/test/dist/jscomp/test/typeof_test.js
index a7b935f37..4c24718ad 100644
--- a/jscomp/test/dist/jscomp/test/typeof_test.js
+++ b/jscomp/test/dist/jscomp/test/typeof_test.js
@@ -8,9 +8,6 @@ function string_or_number(x) {
   const ty = Js__Js_types.classify(x);
   if (/* tag */ typeof ty === "number" || typeof ty === "string") {
     switch (ty) {
-      case /* JSFalse */ 0 :
-      case /* JSTrue */ 1 :
-          return false;
       default:
         return false;
     }