From jQuery migrate docs:

Upgrading libraries such as jQuery can be a lot of work, when breaking changes have been introduced. jQuery Migrate makes this easier, by restoring the APIs that were removed, and additionally shows warnings in the browser console (development version of jQuery Migrate only) when removed and/or deprecated APIs are used.

 

That way you can spot and fix what otherwise would have been errors, until you no longer need jQuery Migrate and can remove it.

Does it look through your files? No. It only warns when deprecated methods have been called from within your code

From jQuery migrate docs:

Upgrading libraries such as jQuery can be a lot of work, when breaking changes have been introduced. jQuery Migrate makes this easier, by restoring the APIs that were removed, and additionally shows warnings in the browser console (development version of jQuery Migrate only) when removed and/or deprecated APIs are used.

That way you can spot and fix what otherwise would have been errors, until you no longer need jQuery Migrate and can remove it.

Does it look through your files? No. It only warns when deprecated methods have been called from within your code

From jQuery migrate docs:

Upgrading libraries such as jQuery can be a lot of work, when breaking changes have been introduced. jQuery Migrate makes this easier, by restoring the APIs that were removed, and additionally shows warnings in the browser console (development version of jQuery Migrate only) when removed and/or deprecated APIs are used.

That way you can spot and fix what otherwise would have been errors, until you no longer need jQuery Migrate and can remove it.

From jQuery migrate docs:

Upgrading libraries such as jQuery can be a lot of work, when breaking changes have been introduced. jQuery Migrate makes this easier, by restoring the APIs that were removed, and additionally shows warnings in the browser console (development version of jQuery Migrate only) when removed and/or deprecated APIs are used.

That way you can spot and fix what otherwise would have been errors, until you no longer need jQuery Migrate and can remove it.

Does it look through your files? No. It only warns when deprecated methods have been called from within your code