A previous article covered debugging a mobile web page with Chrome. This guide explains how to debug a page open in Safari on an iPhone.
Remote Debugging Requirements
You need both a Mac and an iPhone. This workflow is not available from a Windows computer.
Inspect an iPhone Safari Tab from a Mac
Enable Web Inspector on the iPhone. Open Settings → Apps → Safari → Advanced, then turn on Web Inspector.

Open Safari on the Mac and use the Develop menu as shown below:

The target page must also be open in Safari on the iPhone; otherwise it will not appear in the Mac’s Develop menu.
Select the web page you want to inspect. Safari opens its developer tools:
