use a mutex to prevent multiple prompts from opening in loop.

extension/background.js

@@ -1,6 +1,7 @@
 import browser from 'webextension-polyfill'
 import {validateEvent, signEvent, getEventHash, getPublicKey} from 'nostr-tools'
 import {encrypt, decrypt} from 'nostr-tools/nip04'
+import {Mutex} from 'async-mutex'
 
 import {
   PERMISSIONS_REQUIRED,
@@ -8,7 +9,9 @@ import {
   updatePermission
 } from './common'
 
-const prompts = {}
+let openPrompt = null
+let promptMutex = new Mutex()
+let releasePromptMutex = () => {}
 
 browser.runtime.onMessage.addListener(async (req, sender) => {
   let {prompt} = req
@@ -89,25 +92,28 @@ function handlePromptMessage({id, condition, host, level}, sender) {
   switch (condition) {
     case 'forever':
     case 'expirable':
-      prompts[id]?.resolve?.()
+      openPrompt?.resolve?.()
       updatePermission(host, {
         level,
         condition
       })
       break
     case 'single':
-      prompts[id]?.resolve?.()
+      openPrompt?.resolve?.()
       break
     case 'no':
-      prompts[id]?.reject?.()
+      openPrompt?.reject?.()
       break
   }
 
-  delete prompts[id]
+  openPrompt = null
+  releasePromptMutex()
   browser.windows.remove(sender.tab.windowId)
 }
 
-function promptPermission(host, level, params) {
+async function promptPermission(host, level, params) {
+  releasePromptMutex = await promptMutex.acquire()
+
   let id = Math.random().toString().slice(4)
   let qs = new URLSearchParams({
     host,
@@ -117,13 +123,13 @@ function promptPermission(host, level, params) {
   })
 
   return new Promise((resolve, reject) => {
+    openPrompt = {resolve, reject}
+
     browser.windows.create({
       url: `${browser.runtime.getURL('prompt.html')}?${qs.toString()}`,
       type: 'popup',
       width: 340,
       height: 330
     })
-
-    prompts[id] = {resolve, reject}
   })
 }

package.json

@@ -1,6 +1,7 @@
 {
   "dependencies": {
     "@esbuild-plugins/node-globals-polyfill": "^0.1.1",
+    "async-mutex": "^0.3.2",
     "esbuild": "^0.14.11",
     "esbuild-plugin-alias": "^0.2.1",
     "eslint": "^8.6.0",

yarn.lock

@@ -113,6 +113,13 @@ array.prototype.flatmap@^1.2.5:
     define-properties "^1.1.3"
     es-abstract "^1.19.0"
 
+async-mutex@^0.3.2:
+  version "0.3.2"
+  resolved "https://registry.yarnpkg.com/async-mutex/-/async-mutex-0.3.2.tgz#1485eda5bda1b0ec7c8df1ac2e815757ad1831df"
+  integrity sha512-HuTK7E7MT7jZEh1P9GtRW9+aTWiDWWi9InbZ5hjxrnRa39KS4BW04+xLBhYNS2aXhHUIKZSw3gj4Pn1pj+qGAA==
+  dependencies:
+    tslib "^2.3.1"
+
 balanced-match@^1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-1.0.2.tgz#e83e3a7e3f300b34cb9d87f615fa0cbf357690ee"
@@ -1404,6 +1411,11 @@ tr46@~0.0.3:
   resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
   integrity sha1-gYT9NH2snNwYWZLzpmIuFLnZq2o=
 
+tslib@^2.3.1:
+  version "2.3.1"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.3.1.tgz#e8a335add5ceae51aa261d32a490158ef042ef01"
+  integrity sha512-77EbyPPpMz+FRFRuAFlWMtmgUWGe9UOG2Z25NqCwiIjRhOf5iKGuzSe5P2w1laq+FkRy4p+PCuVkJSGkzTEKVw==
+
 tstl@^2.0.7:
   version "2.5.2"
   resolved "https://registry.yarnpkg.com/tstl/-/tstl-2.5.2.tgz#655ae93192e4c18ac74495cea2bf862159775cd9"