What are the differences between jquery version 1 and version 3?

In front-end development, jQuery is a very commonly used JavaScript library, especially in browser compatibility, jQuery plays an indispensable role. In the development process of jQuery, we have also seen the continuous updates of different versions of jQuery libraries. Among them, jQuery 1.x and jQuery 3.x are two significantly different versions. So, what is the difference between jQuery 1.x version and jQuery 3.x version?

1. The difference between jQuery 1.x and jQuery 2.x

First of all, let’s introduce the jQuery 2.x version first, because it is different from the jQuery 1.x version Changes have profound consequences.

In the jQuery 2.x version, some methods and functions of the jQuery library have been heavily optimized to improve robustness and performance. In this version, support for IE6, 7, and 8 browsers has been removed, and support for some new features has been added, such as html5 and css3. The addition of these features affects code size to a certain extent.

At the same time, jQuery 2.x version will continue to support some relatively old browsers, such as Chrome, Firefox, Safari, etc. This is similar to jQuery 1.x.

2. The difference between jQuery 1.x and jQuery 3.x

Next, let’s compare the difference between jQuery 1.x and jQuery 3.x in detail.

① Supported browser types

First of all, jQuery 1.x version and jQuery 3.x version have different supported browser types. The jQuery 1.x version has greater support for the old IE browser. It can support all versions of browsers above IE6. In contrast, jQuery 3.x version focuses more on optimizing new browsers and restricts support for IE browsers, only supporting versions above IE9.

② Newly supported features

As new browsers are constantly updated, browsers support more and more features. In this regard, jQuery 3.x versions are adding support for a variety of new features. For example, new support for Promises, Web Sockets, CSS variables and other features has been added. This way, it works better with modern browsers and frameworks. However, supporting these features also brings some challenges. For example, the increase in the amount of code will bring certain loading speed problems, etc.

③ Code size

In this regard, because the jQuery 3.x version has added support for new features, the number and size of the code has also increased. At the same time, jQuery 3.x version also optimizes and deletes some redundant functions. Therefore, there are differences in code volume and size between versions.

④ Performance Optimization

In terms of performance, jQuery 3.x has greatly improved its performance compared to jQuery 1.x. For example, methods such as ".live()", ".die()", and ".toggle()" have been deleted, and performance bottlenecks such as Deferred objects and dynamically created DOM elements have also been optimized.

In short, the optimization of jQuery 3.x is mainly based on performance and new feature support, and is suitable for modern browser environments, while jQuery 1.x has greater support for old browsers. Since specific project situations are different, choosing to use different versions of the jQuery library should be based on actual needs. The latest version of the jQuery library is indeed more powerful in performance and features, but if there are restrictions on the front-end browser environment, you can choose the jQuery 1.x version.

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