8 files changed, 58 insertions, 26 deletions
diff --git a/cli/js/deno.ts b/cli/js/deno.ts
index d20c64281..c1b074f3d 100644
--- a/cli/js/deno.ts
+++ b/cli/js/deno.ts
@@ -85,7 +85,7 @@ export {
   ShutdownMode,
   shutdown
 } from "./net.ts";
-export { dir, env, exit, isTTY, execPath, hostname } from "./os.ts";
+export { dir, env, exit, isTTY, execPath, hostname, loadavg } from "./os.ts";
 export {
   permissions,
   PermissionName,
diff --git a/cli/js/dispatch.ts b/cli/js/dispatch.ts
index 3d2138953..93f6dc055 100644
--- a/cli/js/dispatch.ts
+++ b/cli/js/dispatch.ts
@@ -80,6 +80,7 @@ export let OP_TRANSPILE: number;
 export let OP_SIGNAL_BIND: number;
 export let OP_SIGNAL_UNBIND: number;
 export let OP_SIGNAL_POLL: number;
+export let OP_LOADAVG: number;
 
 const PLUGIN_ASYNC_HANDLER_MAP: Map<number, AsyncHandler> = new Map();
 
diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index 39303677a..d1770a15a 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -40,6 +40,12 @@ declare namespace Deno {
     stderr: boolean;
   };
 
+  /** Get the loadavg. Requires the `--allow-env` flag.
+   *
+   *       console.log(Deno.loadavg());
+   */
+  export function loadavg(): number[];
+
   /** Get the hostname. Requires the `--allow-env` flag.
    *
    *       console.log(Deno.hostname());
diff --git a/cli/js/os.ts b/cli/js/os.ts
index 275dbdf1d..d3c0d1b72 100644
--- a/cli/js/os.ts
+++ b/cli/js/os.ts
@@ -11,6 +11,14 @@ import * as util from "./util.ts";
 export function isTTY(): { stdin: boolean; stdout: boolean; stderr: boolean } {
   return sendSync(dispatch.OP_IS_TTY);
 }
+/** Get the loadavg.
+ * Requires the `--allow-env` flag.
+ *
+ *       console.log(Deno.loadavg());
+ */
+export function loadavg(): number[] {
+  return sendSync(dispatch.OP_LOADAVG);
+}
 
 /** Get the hostname.
  * Requires the `--allow-env` flag.
diff --git a/cli/js/os_test.ts b/cli/js/os_test.ts
index fa4bf636b..325cbdaa6 100644
--- a/cli/js/os_test.ts
+++ b/cli/js/os_test.ts
@@ -283,6 +283,23 @@ testPerm({ env: false }, function execPathPerm(): void {
   assert(caughtError);
 });
 
+testPerm({ env: true }, function loadavgSuccess(): void {
+  const load = Deno.loadavg();
+  assertEquals(load.length, 3);
+});
+
+testPerm({ env: false }, function loadavgPerm(): void {
+  let caughtError = false;
+  try {
+    Deno.loadavg();
+  } catch (err) {
+    caughtError = true;
+    assert(err instanceof Deno.Err.PermissionDenied);
+    assertEquals(err.name, "PermissionDenied");
+  }
+  assert(caughtError);
+});
+
 testPerm({ env: true }, function hostnameDir(): void {
   assertNotEquals(Deno.hostname(), "");
 });
diff --git a/cli/ops/os.rs b/cli/ops/os.rs
index 8def5ac1e..d1786a6db 100644
--- a/cli/ops/os.rs
+++ b/cli/ops/os.rs
@@ -19,6 +19,7 @@ pub fn init(i: &mut Isolate, s: &State) {
   i.register_op("get_env", s.core_op(json_op(s.stateful_op(op_get_env))));
   i.register_op("get_dir", s.core_op(json_op(s.stateful_op(op_get_dir))));
   i.register_op("hostname", s.core_op(json_op(s.stateful_op(op_hostname))));
+  i.register_op("loadavg", s.core_op(json_op(s.stateful_op(op_loadavg))));
 }
 
 #[derive(Deserialize)]
@@ -158,6 +159,22 @@ fn op_is_tty(
   })))
 }
 
+fn op_loadavg(
+  state: &State,
+  _args: Value,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<JsonOp, ErrBox> {
+  state.check_env()?;
+  match sys_info::loadavg() {
+    Ok(loadavg) => Ok(JsonOp::Sync(json!([
+      loadavg.one,
+      loadavg.five,
+      loadavg.fifteen
+    ]))),
+    Err(_) => Ok(JsonOp::Sync(json!([0f64, 0f64, 0f64]))),
+  }
+}
+
 fn op_hostname(
   state: &State,
   _args: Value,
diff --git a/std/node/os.ts b/std/node/os.ts
index 8facde292..51e5bbd93 100644
--- a/std/node/os.ts
+++ b/std/node/os.ts
@@ -133,12 +133,12 @@ export function hostname(): string {
   return Deno.hostname();
 }
 
-/** Not yet implemented */
+/** Returns an array containing the 1, 5, and 15 minute load averages */
 export function loadavg(): number[] {
   if (Deno.build.os == "win") {
     return [0, 0, 0];
   }
-  notImplemented(SEE_GITHUB_ISSUE);
+  return Deno.loadavg();
 }
 
 /** Not yet implemented */
diff --git a/std/node/os_test.ts b/std/node/os_test.ts
index f13589a4b..f825ae192 100644
--- a/std/node/os_test.ts
+++ b/std/node/os_test.ts
@@ -1,10 +1,5 @@
 const { test } = Deno;
-import {
-  assert,
-  assertThrows,
-  assertEquals,
-  AssertionError
-} from "../testing/asserts.ts";
+import { assert, assertThrows, assertEquals } from "../testing/asserts.ts";
 import * as os from "./os.ts";
 
 test({
@@ -168,26 +163,14 @@ test({
   }
 });
 
-// Method is currently implemented correctly for windows but not for any other os
 test({
   name: "Load average is an array of 3 numbers",
   fn() {
-    try {
-      const result = os.loadavg();
-      assert(result.length == 3);
-      assertEquals(typeof result[0], "number");
-      assertEquals(typeof result[1], "number");
-      assertEquals(typeof result[2], "number");
-    } catch (error) {
-      if (!(Object.getPrototypeOf(error) === Error.prototype)) {
-        const errMsg = `Unexpected error class: ${error.name}`;
-        throw new AssertionError(errMsg);
-      } else if (!error.message.includes("Not implemented")) {
-        throw new AssertionError(
-          "Expected this error to contain 'Not implemented'"
-        );
-      }
-    }
+    const result = os.loadavg();
+    assert(result.length == 3);
+    assertEquals(typeof result[0], "number");
+    assertEquals(typeof result[1], "number");
+    assertEquals(typeof result[2], "number");
   }
 });