Thanks for the reviews from @codemist, @lloan and @Vinnl. I generated a lengthy TODO list in response to the review. Filing it here to make it easier to track against the BIG pr, even though I'll be committing directly to the mpp-1714-staging branch.

TODO:

Global/features:

[ ] Analytics review
[ ] News item count

HTML

src/popup.html

[x] Localize Navigation items
[ ] Update navigation elements to <button> instead of <a>
[ ] Add alt-tag to Close button (.fx-relay-masks-error-message-icon)
[ ] Comment on dynamically populated markup in HTML
[ ] Custom elements <content>, <panel>, etc should all contain a hyphen

Javascript

src/js/popup/popup.js

[ ] Question: Use local storage for state mgmt for persistent items (newsItemCount?)
[ ] State object: remove unused data
[ ] Use lloan suggestion f ([400,409].includes(newRelayAddressResponse.status)) {
[ ] masks.custom.init: Remove commented code
[ ] Use lloan suggestion: matchesSearchFilter
[ ] Check on TODO: Add toggle button back
[ ] Question about destructing: `const { emailsForwardedVal } = await ...
[ ] Use lloan suggestion: domainList === null (or Kaitlyn ?? operator)
[ ] Fix line-breaks: panel.init function
[ ] Consider re-ordering noMasksPanelCreated panel to show by default
[ ] isPremiumSubdomainSet is defined and used multiple times
[ ] Remove extra line-breaks in setRemainingMaskCount
[ ] Rename storyData to something more legible.
[ ] News item issue: isPhoneMaskingAvailable and logicCheck may be unnecessary / duplicate

src/js/background/background.js

[ ] Remove console log
[ ] Add comment on apiBody.used_on = description + ",";
[ ] Investigate FIXME
[ ] Investigate // TODO: Update the domain attribute to be "label"
[ ] Add comment for const localRelayAddresses = Object.keys(localStorageRelayAddresses).
[ ] Use lloan suggestion: return { status: 402 };
[ ] Add comment for return { status: 402 };

mozilla / fx-private-relay-add-on

Popup Refactor (Epic PR to Main) Review TODO List #475