Part 5.2Selecting and typing DOM elements

Selecting elements

DOM selectors may fail, so TypeScript correctly includes null in their result. Check first instead of using a type assertion to silence the warning.

const button = document.querySelector<HTMLButtonElement>("#save");

if (button) {
  button.disabled = true;
}

Handling null

The check is not ceremony: it records that an absent element is expected and dealt with. If an element is genuinely required, throw a helpful error close to the selector rather than using ! throughout the codebase.