In case ajax calls are making a trouble and developer needs more information about what is happening regarding:
- which js code is calling a request
- what URL is called
- what is the response status
- what is the response format
Crome developer console can help a lot. For example, in case we need to check what is happening on Drupal autocomplete changes you need to do following steps:
- Open a page with autocomplete field
- Open Chrome developers tools
- Click tab "Network"
- Clean all current records by clicking icon "Clear" in top left corner
- Start typing autocomplete data
- Check what is displayed in dev tools.