Chartjs-Synchronous XMLHttpRequest when loading charts.js in to a div

To avoid this warning, do not use:

async: false
in any of your $.ajax() calls. This is the only feature of XMLHttpRequest that’s deprecated.

The default is async: true, so if you never use this option at all, your code should be safe if the feature is ever really removed (it probably won’t be — it may be removed from the standards, but I’ll bet browsers will continue to support it for many years).