TS migration. #2288. (#2328)

* Added TS. Updated build and linting config. Added types.

* [ts-migrate][.] Rename files from JS/JSX to TS/TSX

Co-authored-by: ts-migrate <>

* [ts-migrate][.] Run TS Migrate

Co-authored-by: ts-migrate <>

* Corrected files mangled by ts-migrate.

* Updated lint config, minor linting.

* Re-enabled Husky.

* Updated tests and config.

* Reverted webpack devtool config.

* Removed obsolete snapshots.

* Added annotations snap.

* Updated tsconfig includes wrt linting.

* Removed ts-migrate.

Co-authored-by: Timmy Huang <tihuan@users.noreply.github.com>

client/src/util/significantDigits.ts

@@ -0,0 +1,10 @@
+/* 
+    via https://github.com/nodef/extra-number/blob/master/scripts/significantDigits.js
+*/
+
+export default (n: any) => {
+  return n
+    .toExponential()
+    .replace(/e[+\-0-9]*$/, "")
+    .replace(/^0\.?0*|\./, "").length;
+};