diff --git a/cli/js/deno.ts b/cli/js/deno.ts
index 2d16b75cf9..a4b524f8df 100644
--- a/cli/js/deno.ts
+++ b/cli/js/deno.ts
@@ -33,15 +33,12 @@ export {
   stdin,
   stdout,
   stderr,
-  read,
-  readSync,
-  write,
-  writeSync,
   seek,
   seekSync,
   OpenOptions,
   OpenMode
 } from "./files.ts";
+export { read, readSync, write, writeSync } from "./ops/io.ts";
 export { FsEvent, fsEvents } from "./ops/fs_events.ts";
 export {
   EOF,
@@ -101,14 +98,8 @@ export {
   Permissions
 } from "./permissions.ts";
 export { openPlugin } from "./plugins.ts";
-export {
-  kill,
-  run,
-  RunOptions,
-  Process,
-  ProcessStatus,
-  Signal
-} from "./process.ts";
+export { kill } from "./ops/process.ts";
+export { run, RunOptions, Process, ProcessStatus, Signal } from "./process.ts";
 export { readdirSync, readdir } from "./read_dir.ts";
 export { readFileSync, readFile } from "./read_file.ts";
 export { readlinkSync, readlink } from "./read_link.ts";
diff --git a/cli/js/dispatch_minimal_test.ts b/cli/js/dispatch_minimal_test.ts
index 0022bd0c42..724a416981 100644
--- a/cli/js/dispatch_minimal_test.ts
+++ b/cli/js/dispatch_minimal_test.ts
@@ -10,7 +10,7 @@ const readErrorStackPattern = new RegExp(
   `^.*
     at unwrapResponse \\(.*dispatch_minimal\\.ts:.*\\)
     at Object.sendAsyncMinimal \\(.*dispatch_minimal\\.ts:.*\\)
-    at async Object\\.read \\(.*files\\.ts:.*\\).*$`,
+    at async Object\\.read \\(.*io\\.ts:.*\\).*$`,
   "ms"
 );
 
diff --git a/cli/js/files.ts b/cli/js/files.ts
index 21b0105afe..9103ab60bb 100644
--- a/cli/js/files.ts
+++ b/cli/js/files.ts
@@ -10,17 +10,12 @@ import {
   SyncWriter,
   SyncSeeker
 } from "./io.ts";
-import { sendAsyncMinimal, sendSyncMinimal } from "./ops/dispatch_minimal.ts";
 import {
   sendSync as sendSyncJson,
   sendAsync as sendAsyncJson
 } from "./ops/dispatch_json.ts";
 import { close } from "./ops/resources.ts";
-import { OPS_CACHE } from "./runtime.ts";
-
-// This is done because read/write are extremely performance sensitive.
-let OP_READ = -1;
-let OP_WRITE = -1;
+import { read, readSync, write, writeSync } from "./ops/io.ts";
 
 /** Synchronously open a file and return an instance of the `File` object.
  *
@@ -118,100 +113,6 @@ export function create(path: string): Promise<File> {
   return open(path, "w+");
 }
 
-/** Synchronously read from a file ID into an array buffer.
- *
- * Returns `number | EOF` for the operation.
- *
- *      const file = Deno.openSync("/foo/bar.txt");
- *      const buf = new Uint8Array(100);
- *      const nread = Deno.readSync(file.rid, buf);
- *      const text = new TextDecoder().decode(buf);
- */
-export function readSync(rid: number, p: Uint8Array): number | EOF {
-  if (p.length == 0) {
-    return 0;
-  }
-  if (OP_READ < 0) {
-    OP_READ = OPS_CACHE["op_read"];
-  }
-  const nread = sendSyncMinimal(OP_READ, rid, p);
-  if (nread < 0) {
-    throw new Error("read error");
-  } else if (nread == 0) {
-    return EOF;
-  } else {
-    return nread;
-  }
-}
-
-/** Read from a resource ID into an array buffer.
- *
- * Resolves to the `number | EOF` for the operation.
- *
- *       const file = await Deno.open("/foo/bar.txt");
- *       const buf = new Uint8Array(100);
- *       const nread = await Deno.read(file.rid, buf);
- *       const text = new TextDecoder().decode(buf);
- */
-export async function read(rid: number, p: Uint8Array): Promise<number | EOF> {
-  if (p.length == 0) {
-    return 0;
-  }
-  if (OP_READ < 0) {
-    OP_READ = OPS_CACHE["op_read"];
-  }
-  const nread = await sendAsyncMinimal(OP_READ, rid, p);
-  if (nread < 0) {
-    throw new Error("read error");
-  } else if (nread == 0) {
-    return EOF;
-  } else {
-    return nread;
-  }
-}
-
-/** Synchronously write to the resource ID the contents of the array buffer.
- *
- * Resolves to the number of bytes written.
- *
- *       const encoder = new TextEncoder();
- *       const data = encoder.encode("Hello world\n");
- *       const file = Deno.openSync("/foo/bar.txt", {create: true, write: true});
- *       Deno.writeSync(file.rid, data);
- */
-export function writeSync(rid: number, p: Uint8Array): number {
-  if (OP_WRITE < 0) {
-    OP_WRITE = OPS_CACHE["op_write"];
-  }
-  const result = sendSyncMinimal(OP_WRITE, rid, p);
-  if (result < 0) {
-    throw new Error("write error");
-  } else {
-    return result;
-  }
-}
-
-/** Write to the resource ID the contents of the array buffer.
- *
- * Resolves to the number of bytes written.
- *
- *      const encoder = new TextEncoder();
- *      const data = encoder.encode("Hello world\n");
- *      const file = await Deno.open("/foo/bar.txt", {create: true, write: true});
- *      await Deno.write(file.rid, data);
- */
-export async function write(rid: number, p: Uint8Array): Promise<number> {
-  if (OP_WRITE < 0) {
-    OP_WRITE = OPS_CACHE["op_write"];
-  }
-  const result = await sendAsyncMinimal(OP_WRITE, rid, p);
-  if (result < 0) {
-    throw new Error("write error");
-  } else {
-    return result;
-  }
-}
-
 /** Synchronously seek a file ID to the given offset under mode given by `whence`.
  *
  * Returns the number of cursor position.
diff --git a/cli/js/net.ts b/cli/js/net.ts
index 6547628854..3b0525096d 100644
--- a/cli/js/net.ts
+++ b/cli/js/net.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { EOF, Reader, Writer, Closer } from "./io.ts";
-import { read, write } from "./files.ts";
+import { read, write } from "./ops/io.ts";
 import { close } from "./ops/resources.ts";
 import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
 
diff --git a/cli/js/ops/io.ts b/cli/js/ops/io.ts
new file mode 100644
index 0000000000..9f53707b7c
--- /dev/null
+++ b/cli/js/ops/io.ts
@@ -0,0 +1,105 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { sendAsyncMinimal, sendSyncMinimal } from "./dispatch_minimal.ts";
+import { EOF } from "../io.ts";
+// TODO(bartlomieju): remove this import and maybe lazy-initialize
+// OPS_CACHE that belongs only to this module
+import { OPS_CACHE } from "../runtime.ts";
+
+// This is done because read/write are extremely performance sensitive.
+let OP_READ = -1;
+let OP_WRITE = -1;
+
+/** Synchronously read from a file ID into an array buffer.
+ *
+ * Returns `number | EOF` for the operation.
+ *
+ *      const file = Deno.openSync("/foo/bar.txt");
+ *      const buf = new Uint8Array(100);
+ *      const nread = Deno.readSync(file.rid, buf);
+ *      const text = new TextDecoder().decode(buf);
+ */
+export function readSync(rid: number, p: Uint8Array): number | EOF {
+  if (p.length == 0) {
+    return 0;
+  }
+  if (OP_READ < 0) {
+    OP_READ = OPS_CACHE["op_read"];
+  }
+  const nread = sendSyncMinimal(OP_READ, rid, p);
+  if (nread < 0) {
+    throw new Error("read error");
+  } else if (nread == 0) {
+    return EOF;
+  } else {
+    return nread;
+  }
+}
+
+/** Read from a resource ID into an array buffer.
+ *
+ * Resolves to the `number | EOF` for the operation.
+ *
+ *       const file = await Deno.open("/foo/bar.txt");
+ *       const buf = new Uint8Array(100);
+ *       const nread = await Deno.read(file.rid, buf);
+ *       const text = new TextDecoder().decode(buf);
+ */
+export async function read(rid: number, p: Uint8Array): Promise<number | EOF> {
+  if (p.length == 0) {
+    return 0;
+  }
+  if (OP_READ < 0) {
+    OP_READ = OPS_CACHE["op_read"];
+  }
+  const nread = await sendAsyncMinimal(OP_READ, rid, p);
+  if (nread < 0) {
+    throw new Error("read error");
+  } else if (nread == 0) {
+    return EOF;
+  } else {
+    return nread;
+  }
+}
+
+/** Synchronously write to the resource ID the contents of the array buffer.
+ *
+ * Resolves to the number of bytes written.
+ *
+ *       const encoder = new TextEncoder();
+ *       const data = encoder.encode("Hello world\n");
+ *       const file = Deno.openSync("/foo/bar.txt", {create: true, write: true});
+ *       Deno.writeSync(file.rid, data);
+ */
+export function writeSync(rid: number, p: Uint8Array): number {
+  if (OP_WRITE < 0) {
+    OP_WRITE = OPS_CACHE["op_write"];
+  }
+  const result = sendSyncMinimal(OP_WRITE, rid, p);
+  if (result < 0) {
+    throw new Error("write error");
+  } else {
+    return result;
+  }
+}
+
+/** Write to the resource ID the contents of the array buffer.
+ *
+ * Resolves to the number of bytes written.
+ *
+ *      const encoder = new TextEncoder();
+ *      const data = encoder.encode("Hello world\n");
+ *      const file = await Deno.open("/foo/bar.txt", {create: true, write: true});
+ *      await Deno.write(file.rid, data);
+ */
+export async function write(rid: number, p: Uint8Array): Promise<number> {
+  if (OP_WRITE < 0) {
+    OP_WRITE = OPS_CACHE["op_write"];
+  }
+  const result = await sendAsyncMinimal(OP_WRITE, rid, p);
+  if (result < 0) {
+    throw new Error("write error");
+  } else {
+    return result;
+  }
+}
diff --git a/cli/js/ops/permissions.ts b/cli/js/ops/permissions.ts
new file mode 100644
index 0000000000..783b1b297e
--- /dev/null
+++ b/cli/js/ops/permissions.ts
@@ -0,0 +1,24 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { sendSync } from "./dispatch_json.ts";
+
+// TODO(bartlomieju): duplicated in `cli/js/permissions.ts` as
+// `PermissionState
+export type PermissionResponse = "granted" | "denied" | "prompt";
+
+interface PermissionRequest {
+  name: string;
+  url?: string;
+  path?: string;
+}
+
+export function query(desc: PermissionRequest): PermissionResponse {
+  return sendSync("op_query_permission", desc).state;
+}
+
+export function revoke(desc: PermissionRequest): PermissionResponse {
+  return sendSync("op_revoke_permission", desc).state;
+}
+
+export function request(desc: PermissionRequest): PermissionResponse {
+  return sendSync("op_request_permission", desc).state;
+}
diff --git a/cli/js/ops/plugins.ts b/cli/js/ops/plugins.ts
new file mode 100644
index 0000000000..878ea1c66d
--- /dev/null
+++ b/cli/js/ops/plugins.ts
@@ -0,0 +1,12 @@
+import { sendSync } from "./dispatch_json.ts";
+
+interface OpenPluginResponse {
+  rid: number;
+  ops: {
+    [name: string]: number;
+  };
+}
+
+export function openPlugin(filename: string): OpenPluginResponse {
+  return sendSync("op_open_plugin", { filename });
+}
diff --git a/cli/js/ops/process.ts b/cli/js/ops/process.ts
new file mode 100644
index 0000000000..31ce0b33ef
--- /dev/null
+++ b/cli/js/ops/process.ts
@@ -0,0 +1,47 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { sendSync, sendAsync } from "./dispatch_json.ts";
+import { assert } from "../util.ts";
+
+/** Send a signal to process under given PID. Unix only at this moment.
+ * If pid is negative, the signal will be sent to the process group identified
+ * by -pid.
+ * Requires the `--allow-run` flag.
+ */
+export function kill(pid: number, signo: number): void {
+  sendSync("op_kill", { pid, signo });
+}
+
+interface RunStatusResponse {
+  gotSignal: boolean;
+  exitCode: number;
+  exitSignal: number;
+}
+
+export async function runStatus(rid: number): Promise<RunStatusResponse> {
+  return await sendAsync("op_run_status", { rid });
+}
+
+interface RunRequest {
+  args: string[];
+  cwd?: string;
+  env?: Array<[string, string]>;
+  stdin: string;
+  stdout: string;
+  stderr: string;
+  stdinRid: number;
+  stdoutRid: number;
+  stderrRid: number;
+}
+
+interface RunResponse {
+  rid: number;
+  pid: number;
+  stdinRid: number | null;
+  stdoutRid: number | null;
+  stderrRid: number | null;
+}
+
+export function run(request: RunRequest): RunResponse {
+  assert(request.args.length > 0);
+  return sendSync("op_run", request);
+}
diff --git a/cli/js/ops/signal.ts b/cli/js/ops/signal.ts
new file mode 100644
index 0000000000..7f9304a82e
--- /dev/null
+++ b/cli/js/ops/signal.ts
@@ -0,0 +1,14 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { sendSync, sendAsync } from "./dispatch_json.ts";
+
+export function bindSignal(signo: number): { rid: number } {
+  return sendSync("op_signal_bind", { signo });
+}
+
+export async function pollSignal(rid: number): Promise<{ done: boolean }> {
+  return await sendAsync("op_signal_poll", { rid });
+}
+
+export function unbindSignal(rid: number): void {
+  sendSync("op_signal_unbind", { rid });
+}
diff --git a/cli/js/ops/timers.ts b/cli/js/ops/timers.ts
new file mode 100644
index 0000000000..bc7fe6453e
--- /dev/null
+++ b/cli/js/ops/timers.ts
@@ -0,0 +1,10 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { sendSync, sendAsync } from "./dispatch_json.ts";
+
+export function stopGlobalTimer(): void {
+  sendSync("op_global_timer_stop");
+}
+
+export async function startGlobalTimer(timeout: number): Promise<void> {
+  await sendAsync("op_global_timer", { timeout });
+}
diff --git a/cli/js/ops/web_worker.ts b/cli/js/ops/web_worker.ts
new file mode 100644
index 0000000000..329323e2e5
--- /dev/null
+++ b/cli/js/ops/web_worker.ts
@@ -0,0 +1,11 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { sendSync } from "./dispatch_json.ts";
+
+export function postMessage(data: Uint8Array): void {
+  sendSync("op_worker_post_message", {}, data);
+}
+
+export function close(): void {
+  sendSync("op_worker_close");
+}
diff --git a/cli/js/ops/worker_host.ts b/cli/js/ops/worker_host.ts
new file mode 100644
index 0000000000..a409d2c77a
--- /dev/null
+++ b/cli/js/ops/worker_host.ts
@@ -0,0 +1,29 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+/* eslint-disable @typescript-eslint/no-explicit-any */
+import { sendAsync, sendSync } from "./dispatch_json.ts";
+
+export function createWorker(
+  specifier: string,
+  hasSourceCode: boolean,
+  sourceCode: string,
+  name?: string
+): { id: number } {
+  return sendSync("op_create_worker", {
+    specifier,
+    hasSourceCode,
+    sourceCode,
+    name
+  });
+}
+
+export function hostTerminateWorker(id: number): void {
+  sendSync("op_host_terminate_worker", { id });
+}
+
+export function hostPostMessage(id: number, data: Uint8Array): void {
+  sendSync("op_host_post_message", { id }, data);
+}
+
+export async function hostGetMessage(id: number): Promise<any> {
+  return await sendAsync("op_host_get_message", { id });
+}
diff --git a/cli/js/permissions.ts b/cli/js/permissions.ts
index d3f3d163a1..8fad8b691a 100644
--- a/cli/js/permissions.ts
+++ b/cli/js/permissions.ts
@@ -1,5 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { sendSync } from "./ops/dispatch_json.ts";
+import * as permissionsOps from "./ops/permissions.ts";
 
 /** Permissions as granted by the caller
  * See: https://w3c.github.io/permissions/#permission-registry
@@ -60,7 +60,7 @@ export class Permissions {
    *       }
    */
   async query(desc: PermissionDescriptor): Promise<PermissionStatus> {
-    const { state } = sendSync("op_query_permission", desc);
+    const state = permissionsOps.query(desc);
     return new PermissionStatus(state);
   }
 
@@ -69,7 +69,7 @@ export class Permissions {
    *       assert(status.state !== "granted")
    */
   async revoke(desc: PermissionDescriptor): Promise<PermissionStatus> {
-    const { state } = sendSync("op_revoke_permission", desc);
+    const state = permissionsOps.revoke(desc);
     return new PermissionStatus(state);
   }
 
@@ -82,7 +82,7 @@ export class Permissions {
    *       }
    */
   async request(desc: PermissionDescriptor): Promise<PermissionStatus> {
-    const { state } = sendSync("op_request_permission", desc);
+    const state = permissionsOps.request(desc);
     return new PermissionStatus(state);
   }
 }
diff --git a/cli/js/plugins.ts b/cli/js/plugins.ts
index 2dbee4c748..061193b4f9 100644
--- a/cli/js/plugins.ts
+++ b/cli/js/plugins.ts
@@ -1,4 +1,4 @@
-import { sendSync } from "./ops/dispatch_json.ts";
+import { openPlugin as openPluginOp } from "./ops/plugins.ts";
 import { core } from "./core.ts";
 
 export interface AsyncHandler {
@@ -50,16 +50,7 @@ class PluginImpl implements Plugin {
   }
 }
 
-interface OpenPluginResponse {
-  rid: number;
-  ops: {
-    [name: string]: number;
-  };
-}
-
 export function openPlugin(filename: string): Plugin {
-  const response: OpenPluginResponse = sendSync("op_open_plugin", {
-    filename
-  });
+  const response = openPluginOp(filename);
   return new PluginImpl(response.rid, response.ops);
 }
diff --git a/cli/js/process.ts b/cli/js/process.ts
index dc1af51ce9..3e5cc8ea01 100644
--- a/cli/js/process.ts
+++ b/cli/js/process.ts
@@ -1,11 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
 import { File } from "./files.ts";
 import { close } from "./ops/resources.ts";
 import { ReadCloser, WriteCloser } from "./io.ts";
 import { readAll } from "./buffer.ts";
 import { assert, unreachable } from "./util.ts";
 import { build } from "./build.ts";
+import { kill, runStatus as runStatusOp, run as runOp } from "./ops/process.ts";
 
 /** How to handle subprocess stdio.
  *
@@ -31,16 +31,8 @@ export interface RunOptions {
   stdin?: ProcessStdio | number;
 }
 
-interface RunStatusResponse {
-  gotSignal: boolean;
-  exitCode: number;
-  exitSignal: number;
-}
-
 async function runStatus(rid: number): Promise<ProcessStatus> {
-  const res = (await sendAsync("op_run_status", {
-    rid
-  })) as RunStatusResponse;
+  const res = await runStatusOp(rid);
 
   if (res.gotSignal) {
     const signal = res.exitSignal;
@@ -51,15 +43,6 @@ async function runStatus(rid: number): Promise<ProcessStatus> {
   }
 }
 
-/** Send a signal to process under given PID. Unix only at this moment.
- * If pid is negative, the signal will be sent to the process group identified
- * by -pid.
- * Requires the `--allow-run` flag.
- */
-export function kill(pid: number, signo: number): void {
-  sendSync("op_kill", { pid, signo });
-}
-
 export class Process {
   readonly rid: number;
   readonly pid: number;
@@ -220,7 +203,7 @@ export function run(opt: RunOptions): Process {
     stderrRid
   };
 
-  const res = sendSync("op_run", req) as RunResponse;
+  const res = runOp(req);
   return new Process(res);
 }
 
diff --git a/cli/js/runtime_worker.ts b/cli/js/runtime_worker.ts
index 9cfd9229ca..2b1dba088f 100644
--- a/cli/js/runtime_worker.ts
+++ b/cli/js/runtime_worker.ts
@@ -16,7 +16,7 @@ import {
   windowOrWorkerGlobalScopeProperties,
   eventTargetProperties
 } from "./globals.ts";
-import { sendSync } from "./ops/dispatch_json.ts";
+import * as webWorkerOps from "./ops/web_worker.ts";
 import { log } from "./util.ts";
 import { TextEncoder } from "./web/text_encoding.ts";
 import * as runtime from "./runtime.ts";
@@ -31,7 +31,7 @@ export const onerror: (e: { data: any }) => void = (): void => {};
 export function postMessage(data: any): void {
   const dataJson = JSON.stringify(data);
   const dataIntArray = encoder.encode(dataJson);
-  sendSync("op_worker_post_message", {}, dataIntArray);
+  webWorkerOps.postMessage(dataIntArray);
 }
 
 let isClosing = false;
@@ -43,7 +43,7 @@ export function close(): void {
   }
 
   isClosing = true;
-  sendSync("op_worker_close");
+  webWorkerOps.close();
 }
 
 export async function workerMessageRecvCallback(data: string): Promise<void> {
diff --git a/cli/js/signals.ts b/cli/js/signals.ts
index 71ac32ae91..2715cfa508 100644
--- a/cli/js/signals.ts
+++ b/cli/js/signals.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { Signal } from "./process.ts";
-import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
+import { bindSignal, pollSignal, unbindSignal } from "./ops/signal.ts";
 import { build } from "./build.ts";
 
 /**
@@ -105,16 +105,13 @@ export class SignalStream
   /** The flag, which is true when the stream is disposed. */
   private disposed = false;
   constructor(signo: number) {
-    this.rid = sendSync("op_signal_bind", { signo }).rid;
+    this.rid = bindSignal(signo).rid;
     this.loop();
   }
 
   private async pollSignal(): Promise<boolean> {
-    return (
-      await sendAsync("op_signal_poll", {
-        rid: this.rid
-      })
-    ).done;
+    const res = await pollSignal(this.rid);
+    return res.done;
   }
 
   private async loop(): Promise<void> {
@@ -143,6 +140,6 @@ export class SignalStream
       throw new Error("The stream has already been disposed.");
     }
     this.disposed = true;
-    sendSync("op_signal_unbind", { rid: this.rid });
+    unbindSignal(this.rid);
   }
 }
diff --git a/cli/js/timers.ts b/cli/js/timers.ts
index 31f81332a2..844a0b2047 100644
--- a/cli/js/timers.ts
+++ b/cli/js/timers.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { assert } from "./util.ts";
-import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
+import { startGlobalTimer, stopGlobalTimer } from "./ops/timers.ts";
 import { RBTree } from "./rbtree.ts";
 
 const { console } = globalThis;
@@ -26,7 +26,7 @@ const dueTree = new RBTree<DueNode>((a, b) => a.due - b.due);
 
 function clearGlobalTimeout(): void {
   globalTimeoutDue = null;
-  sendSync("op_global_timer_stop");
+  stopGlobalTimer();
 }
 
 let pendingEvents = 0;
@@ -51,7 +51,7 @@ async function setGlobalTimeout(due: number, now: number): Promise<void> {
   // some timeout/defer is put in place to allow promise resolution.
   // Ideally `clearGlobalTimeout` doesn't return until this op is resolved, but
   // I'm not if that's possible.
-  await sendAsync("op_global_timer", { timeout });
+  await startGlobalTimer(timeout);
   pendingEvents--;
   // eslint-disable-next-line @typescript-eslint/no-use-before-define
   fireTimers();
diff --git a/cli/js/web/fetch.ts b/cli/js/web/fetch.ts
index fbe795b4ad..d9918ba14a 100644
--- a/cli/js/web/fetch.ts
+++ b/cli/js/web/fetch.ts
@@ -10,7 +10,7 @@ import { TextDecoder, TextEncoder } from "./text_encoding.ts";
 import { DenoBlob, bytesSymbol as blobBytesSymbol } from "./blob.ts";
 import { Headers } from "./headers.ts";
 import * as io from "../io.ts";
-import { read } from "../files.ts";
+import { read } from "../ops/io.ts";
 import { close } from "../ops/resources.ts";
 import { Buffer } from "../buffer.ts";
 import { FormData } from "./form_data.ts";
diff --git a/cli/js/workers.ts b/cli/js/workers.ts
index 421975e200..4f8cf54ae6 100644
--- a/cli/js/workers.ts
+++ b/cli/js/workers.ts
@@ -1,6 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import { sendAsync, sendSync } from "./ops/dispatch_json.ts";
+import {
+  createWorker,
+  hostTerminateWorker,
+  hostPostMessage,
+  hostGetMessage
+} from "./ops/worker_host.ts";
 import { log } from "./util.ts";
 import { TextDecoder, TextEncoder } from "./web/text_encoding.ts";
 /*
@@ -23,39 +28,12 @@ function decodeMessage(dataIntArray: Uint8Array): any {
   return JSON.parse(dataJson);
 }
 
-function createWorker(
-  specifier: string,
-  hasSourceCode: boolean,
-  sourceCode: Uint8Array,
-  name?: string
-): { id: number } {
-  return sendSync("op_create_worker", {
-    specifier,
-    hasSourceCode,
-    sourceCode: new TextDecoder().decode(sourceCode),
-    name
-  });
-}
-
-function hostTerminateWorker(id: number): void {
-  sendSync("op_host_terminate_worker", { id });
-}
-
-function hostPostMessage(id: number, data: any): void {
-  const dataIntArray = encodeMessage(data);
-  sendSync("op_host_post_message", { id }, dataIntArray);
-}
-
 interface WorkerEvent {
   event: "error" | "msg" | "close";
   data?: any;
   error?: any;
 }
 
-async function hostGetMessage(id: number): Promise<any> {
-  return await sendAsync("op_host_get_message", { id });
-}
-
 export interface Worker {
   onerror?: (e: any) => void;
   onmessage?: (e: { data: any }) => void;
@@ -95,7 +73,7 @@ export class WorkerImpl extends EventTarget implements Worker {
 
     this.name = options?.name ?? "unknown";
     const hasSourceCode = false;
-    const sourceCode = new Uint8Array();
+    const sourceCode = decoder.decode(new Uint8Array());
 
     /* TODO(bartlomieju):
     // Handle blob URL.
@@ -185,7 +163,7 @@ export class WorkerImpl extends EventTarget implements Worker {
       return;
     }
 
-    hostPostMessage(this.id, data);
+    hostPostMessage(this.id, encodeMessage(data));
   }
 
   terminate(): void {