Locks.mode

// Should show "exclusive" (the default)
navigator.locks.request("my_resource", show_lock_properties);

// Should show "exclusive"
navigator.locks.request("my_resource", {mode: "exclusive"}, show_lock_properties);

// Should show "shared"
navigator.locks.request("my_resource", {mode: "shared"}, show_lock_properties);

function show_lock_properties(lock) {
  console.log(`The lock name is: ${lock.name}`);
  console.log(`The lock mode is: ${lock.mode}`);
}