querySelector method Null safety
- String selector
Seaches for the first descendant node matching the given selectors, using a preorder traversal.
NOTE: Not all selectors from selectors level 4 are implemented. For example, nth-child does not implement An+B syntax and *-of-type is not implemented. If a selector is not implemented this method will throw UnimplementedError.
Element? querySelector(String selector) => query.querySelector(this, selector);