Function checkbox

checkbox(
domIdOrEl: string | HTMLInputElement,
onChanged?: (currentValue: boolean) => void,
): { get checked(): boolean; set checked(value: boolean): void }
Quick access to value. Provide a checkbox by string id or object reference. If a callback is supplied, it will be called when the checkbox changes value.
```
const opt = checkbox(`#chkMate`);
opt.checked; // Gets/sets

const opt = checkbox(document.getElementById(`#chkMate`), newVal => {
 if (newVal) ...
});
```
Parameters
- domIdOrEl: string | HTMLInputElement
- OptionalonChanged: (currentValue: boolean) => void
Returns { get checked(): boolean; set checked(value: boolean): void }