Function getExtension

getExtension(pathname): string
Return the extension of the path. Pop the last value of a list after path is split by question mark and comma.
Parameters
- pathname: string
  The path to process.
Returns string
The extension.
Example
```
pc.path.getExtension("/path/to/file.txt"); // returns ".txt"
pc.path.getExtension("/path/to/file.jpg"); // returns ".jpg"
pc.path.getExtension("/path/to/file.txt?function=getExtension"); // returns ".txt"
```
- Defined in engine/src/core/path.js:142