Function elementExists

elementExists(target: undefined | null | Target): boolean
Checks if the specified target exists in the DOM.
Parameters
- target: undefined | null | Target
  Element, EventTarget, or CSS selector.
Returns boolean
true if the specified target exists.
Remarks
We allow null or undefined as well because a null or undefined element technically doesn't exist.
Example
HTML
```
<ul>
  <li id="item-1">Item 1</li>
  <li id="item-2">Item 2</li>
</ul>
```
Code
```
elementExists("#item-1");
// true

elementExists(findElement("#item-1"));
// true

elementExists("#item-3");
// false
```
- Defined in src/elements/elementExists.ts:40