However, it’s not always obvious how to debug that KML content. Google Earth doesn’t have a full set of tools like Chrome Developer Tools. However, it does allow you to view console output, so console.log() output, as well as errors that would normally appear in the Chrome console or Firebug will appear in the console instead. Note, Google Earth does not allow the presentation of system dialogs (namely the functions alert, confirm, and prompt).
Here’s some quick tips on how to get it to work:
Here's a screenshot from Mac OS X:
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