Started with jquery 1.4, should I care about previous versions?

I have a fair knowledge about Javascript, I started with jQuery 1.4 a week back and I have gone through s开发者_如何学运维ome examples. It's very interesting to use it with my application. But my concern is, should I care about previous versions? Should I know what the downsides are of the previous version?

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Always use the very latest version.

Learning about fixed bugs is interesting in the old versions, though your time is probably better spent learning and trying out the current version's features.

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The only reason to really care about previous versions is for supporting legacy apps that haven't updated and are tied to an earlier version. But since jQuery is pretty good about backwards compatibility and the cost of upgrading is so low, people tend to upgrade fairly soon. I'd say focus on the current version

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In my opinion, you only need to concern yourself with the limitations of previous versions of jquery if you're working on a project that uses a previous version. As far as I know, the 1.4 adds a few built-in functions that make some things easier or negate the use of some plugins.

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No you should not because newer jquery versions cover previous ones, you just may need to know differences between versions in case you got a project which already using previous version.

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Should i care about previous versions?

You should be more specific about this but you need to make sure that the sites developed with previous versions run fine. Knowing limitations of previous version helps you know how better tool you have now in your hands. The points is you now have something better in your hands.

should i know What are the downsides of the previous version?

Not necessarily because downsides are gone with the new version.