ExtJs riding on top of jQuery adapter

I understand that we can actually run extjs on top of a jquery adapter, i.e.

But what is the reason for doing that? Can I not just include both libraries separately and use them indepedently,开发者_StackOverflow i.e using jQuery codes in extjs and vice versa...

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There's no reason that I know of that you couldn't use ext-all on top of ext-base for a project that also had jQuery.

You could make an argument that if you simply had to have jQuery using it as your base would save you the (small, 25kb minified) weight of the ext-base.js file.