Function getUrlParam

getUrlParam(url, param, options?): string | string[] | null
Returns the value of the specified query parameter in the input URL.

Usage:
```
const p1 = getUrlParam('http://example.com/?t1=1&t2=2&t3=3&t4=4', 't3');
const p2 = getUrlParam('http://example.com/?t1=1&t2=2&t3=3&t4=4', 't4');
console.log(p1, p2);
```
Output:
```
3 4
```
Parameters
- url: string
  The URL string.
- param: string
  The query parameter to retrieve the value for.
- options: {
  returnArray?: boolean;
  } = {}
  The options object.
  - Optional returnArray?: boolean
    Whether to return an array of values for the specified query parameter. Default is false.
Returns string | string[] | null
The value of the specified query parameter, or an empty string if the parameter is not found.
- Defined in url.ts:60