2 files changed, 193 insertions, 0 deletions
diff --git a/cli/js/web/navigator.ts b/cli/js/web/navigator.ts
new file mode 100644
index 000000000..351c311d0
--- /dev/null
+++ b/cli/js/web/navigator.ts
@@ -0,0 +1,12 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { PermissionsImpl as Permissions } from "./permissions.ts";
+
+export class NavigatorImpl implements Navigator {
+  permissions = new Permissions();
+}
+
+Object.defineProperty(NavigatorImpl, "name", {
+  value: "Navigator",
+  configurable: true,
+});
diff --git a/cli/js/web/permissions.ts b/cli/js/web/permissions.ts
new file mode 100644
index 000000000..b8ddc26a7
--- /dev/null
+++ b/cli/js/web/permissions.ts
@@ -0,0 +1,181 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import * as permissionsOps from "../ops/permissions.ts";
+import { EventTargetImpl as EventTarget } from "./event_target.ts";
+
+const permissionNames = [
+  "read",
+  "write",
+  "net",
+  "env",
+  "run",
+  "plugin",
+  "hrtime",
+] as const;
+
+type PermissionName = typeof permissionNames[number];
+
+interface RunPermissionDescriptor {
+  name: "run";
+}
+
+interface ReadPermissionDescriptor {
+  name: "read";
+  path?: string;
+}
+
+interface WritePermissionDescriptor {
+  name: "write";
+  path?: string;
+}
+
+interface NetPermissionDescriptor {
+  name: "net";
+  url?: string;
+}
+
+interface EnvPermissionDescriptor {
+  name: "env";
+}
+
+interface PluginPermissionDescriptor {
+  name: "plugin";
+}
+
+interface HrtimePermissionDescriptor {
+  name: "hrtime";
+}
+
+type DenoPermissionDescriptor =
+  | RunPermissionDescriptor
+  | ReadPermissionDescriptor
+  | WritePermissionDescriptor
+  | NetPermissionDescriptor
+  | EnvPermissionDescriptor
+  | PluginPermissionDescriptor
+  | HrtimePermissionDescriptor;
+
+interface StatusCacheValue {
+  state: PermissionState;
+  status: PermissionStatusImpl;
+}
+
+export class PermissionStatusImpl extends EventTarget
+  implements PermissionStatus {
+  #state: { state: PermissionState };
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  onchange: ((this: PermissionStatus, event: Event) => any) | null = null;
+
+  get state(): PermissionState {
+    return this.#state.state;
+  }
+
+  constructor(state: { state: PermissionState }) {
+    super();
+    this.#state = state;
+  }
+
+  dispatchEvent(event: Event): boolean {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    let dispatched = super.dispatchEvent(event as any);
+    if (dispatched && this.onchange) {
+      this.onchange.call(this, event);
+      dispatched = !event.defaultPrevented;
+    }
+    return dispatched;
+  }
+
+  get [Symbol.toStringTag](): string {
+    return "PermissionStatus";
+  }
+}
+
+/** A cache of `PermissionStatus` objects and their last known state. */
+const statusCache = new Map<string, StatusCacheValue>();
+
+/** Cache the state of a descriptor and return its `PermissionStatus`. */
+function cache(
+  desc: DenoPermissionDescriptor,
+  state: PermissionState
+): PermissionStatusImpl {
+  let key = desc.name;
+  if ((desc.name === "read" || desc.name === "write") && desc.path) {
+    key += `-${desc.path}`;
+  } else if (desc.name === "net" && desc.url) {
+    key += `-${desc.url}`;
+  }
+  if (statusCache.has(key)) {
+    const status = statusCache.get(key)!;
+    if (status.state !== state) {
+      status.state = state;
+      status.status.dispatchEvent(new Event("change", { cancelable: false }));
+    }
+    return status.status;
+  }
+  const status: { state: PermissionState; status?: PermissionStatusImpl } = {
+    state,
+  };
+  status.status = new PermissionStatusImpl(status);
+  statusCache.set(key, status as StatusCacheValue);
+  return status.status;
+}
+
+function isValidDescriptor(
+  desc: PermissionDescriptor | DenoPermissionDescriptor
+): desc is DenoPermissionDescriptor {
+  return permissionNames.includes(desc.name as PermissionName);
+}
+
+export class PermissionsImpl implements Permissions {
+  query(
+    desc: PermissionDescriptor | DenoPermissionDescriptor
+  ): Promise<PermissionStatus> {
+    if (!isValidDescriptor(desc)) {
+      return Promise.reject(
+        new TypeError(
+          `The provided value "${desc.name}" is not a valid permission name.`
+        )
+      );
+    }
+    const state = permissionsOps.query(desc);
+    return Promise.resolve(cache(desc, state) as PermissionStatus);
+  }
+
+  revoke(
+    desc: PermissionDescriptor | DenoPermissionDescriptor
+  ): Promise<PermissionStatus> {
+    if (!isValidDescriptor(desc)) {
+      return Promise.reject(
+        new TypeError(
+          `The provided value "${desc.name}" is not a valid permission name.`
+        )
+      );
+    }
+    const state = permissionsOps.revoke(desc);
+    return Promise.resolve(cache(desc, state) as PermissionStatus);
+  }
+
+  request(
+    desc: PermissionDescriptor | DenoPermissionDescriptor
+  ): Promise<PermissionStatus> {
+    if (!isValidDescriptor(desc)) {
+      return Promise.reject(
+        new TypeError(
+          `The provided value "${desc.name}" is not a valid permission name.`
+        )
+      );
+    }
+    const state = permissionsOps.request(desc);
+    return Promise.resolve(cache(desc, state) as PermissionStatus);
+  }
+}
+
+Object.defineProperty(PermissionStatusImpl, "name", {
+  value: "PermissionStatus",
+  configurable: true,
+});
+Object.defineProperty(PermissionsImpl, "name", {
+  value: "Permissions",
+  configurable: true,
+});