Port password confirmation functionality to TypeScript

app/javascript/retrospring/features/settings/password.ts

@@ -0,0 +1,14 @@
+/*
+# see GitHub issue #11
+($ document).on "submit", "form#edit_user", (evt) ->
+  if ($ "input#user_current_password").val().length == 0
+    evt.preventDefault()
+    $("button[data-target=#modal-passwd]").trigger 'click'
+*/
+
+export function userSubmitHandler(event: Event): void {
+  if (document.querySelector<HTMLInputElement>('#user_current_password').value.length === 0) {
+    event.preventDefault();
+    document.querySelector<HTMLButtonElement>('[data-target=#modal-passwd]').click();
+  }
+}