1 files changed, 29 insertions, 3 deletions
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index a48105559..16a444098 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -247,6 +247,8 @@ delete Object.prototype.__proto__;
 
   const navigator = webidl.createBranded(Navigator);
 
+  let numCpus;
+
   ObjectDefineProperties(Navigator.prototype, {
     gpu: {
       configurable: true,
@@ -256,6 +258,14 @@ delete Object.prototype.__proto__;
         return webgpu.gpu;
       },
     },
+    hardwareConcurrency: {
+      configurable: true,
+      enumerable: true,
+      get() {
+        webidl.assertBranded(this, Navigator);
+        return numCpus;
+      },
+    },
   });
 
   class WorkerNavigator {
@@ -279,6 +289,14 @@ delete Object.prototype.__proto__;
         return webgpu.gpu;
       },
     },
+    hardwareConcurrency: {
+      configurable: true,
+      enumerable: true,
+      get() {
+        webidl.assertBranded(this, Navigator);
+        return numCpus;
+      },
+    },
   });
 
   // https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope
@@ -491,12 +509,13 @@ delete Object.prototype.__proto__;
       pid,
       ppid,
       unstableFlag,
+      cpuCount,
     } = runtimeOptions;
 
     if (locationHref != null) {
       location.setLocationHref(locationHref);
     }
-
+    numCpus = cpuCount;
     registerErrors();
 
     const internalSymbol = Symbol("Deno.internal");
@@ -566,10 +585,17 @@ delete Object.prototype.__proto__;
       runtimeOptions,
       internalName ?? name,
     );
-    const { unstableFlag, pid, noColor, args, location: locationHref } =
-      runtimeOptions;
+    const {
+      unstableFlag,
+      pid,
+      noColor,
+      args,
+      location: locationHref,
+      cpuCount,
+    } = runtimeOptions;
 
     location.setLocationHref(locationHref);
+    numCpus = cpuCount;
     registerErrors();
 
     pollForMessages();