Drop Babel in favor of esm and TypeScript (#1726)

To get some meaningful errors during feature development, I thought it'd be useful to use TypeScript on `features.js` only, hoping to keep it contained to that file.

@sindresorhus suggested we just extend it the whole extension and maybe that can be done incrementally, without having to necessarily use types on everything.

1 files changed, 24 insertions, 0 deletions

diff --git a/source/features/hide-navigation-hover-highlight.tsx b/source/features/hide-navigation-hover-highlight.tsx
new file mode 100644
index 00000000..d254c1bc
--- /dev/null
+++ b/source/features/hide-navigation-hover-highlight.tsx
@@ -0,0 +1,24 @@
+/*
+Some lists like notifications, file lists, and issue lists,
+are highlighted as you move the mouse over them. This highlight
+is useful when navigating via the keyboard (j/k), but annoying
+when just moving the mouse around.
+
+This feature will hide the highlight until the first keyboard
+navigation, then it will be displayed until the next full reload.
+*/
+import features from '../libs/features';
+
+const className = 'rgh-no-navigation-highlight';
+
+function init() {
+	document.body.classList.add(className);
+	document.body.addEventListener('navigation:keydown', () => {
+		document.body.classList.remove(className);
+	}, {once: true});
+}
+
+features.add({
+	id: 'hide-navigation-hover-highlight',
+	init
+});