HH\Map::firstKey

Returns the first key in the current Map

public function firstKey(): ?Tk;

Returns

• ?Tk - The first key in the current Map, or null if the Map is empty.

Examples

The following example gets the first key from Map. An empty Map will return null as its first key.

$m = Map {
  'red' => '#ff0000',
  'green' => '#00ff00',
  'blue' => '#0000ff',
  'yellow' => '#ffff00',
};
\var_dump($m->firstKey());

$m = Map {};
\var_dump($m->firstKey());