How to Maintain Performance when Using jQuery

How to Maintain Performance when Using jQuery

If you’ve been in the scripting community for any amount of time, then you’ve probably at least heard of jQuery. In basic terms, jQuery is a script library for Javascript. This means that it’s a repository of thousands of different scripting extensions that can be used alongside Javascript to do things that go beyond the ordinary functions of Javascript. For example, it can be used to add animated content to websites, which isn’t a normal function of Javascript. Additionally, using jQuery gives you access to a ton of scripts that have been written by other people in the scripting community, and they’re all available for free. It also boasts an active community that is always willing to help users both new and old with particular problems or issues they’re having with jQuery. Because of this, and because jQuery is built to be very accessibly, it’s very easy to use and easy to get into. However, there are times when its ease of use can lead users to not uphold the best practices of using it, which can lead to performance issues later on down the line. This article gives some tips about how to maintain the integrity of jQuery projects so that they don’t become bloated or optimized throughout the development process.

Load CDN-hosted jQueryLoad CDN-hosted jQuery

Because jQuery is open source, there are actually a bunch of different versions of it floating around out there that have been manipulated to work for a specific kind of project. Usually this is done by a big company, such as Google, that wants a specific Content Delivery Network (CDN). If you’re working on a similar kind of project, a version of jQuery geared toward that type of project will probably load faster and perform better.

Don’t modify the DOM into a loop
Updating the DOM is a useful thing to do, and it’s very possible to accomplish that with Javascript and jQuery. Manipulating it, however, consumes a lot of resources that can make your performance rates plummet. Make sure to never manipulate the DOM into a loop, and if you have to manipulate it at all, append it after the loop.

Stay up to dateStay up to date

This is really kind of a common sense topic. It’s always best to stay up to date with the latest updates to jQuery. Each version update includes performance updates and advancements and bug fixes that can and will improve the speed and efficiency of jQuery.

Prioritize content above the fold
It’s easy to lose sight of how minor things can have an effect on performance, especially in a big project. Part of upholding best practices is to prioritize correctly, which doesn’t make a big difference for an individual line of code or element, but can make a big difference in the long run over a big project.

Use ID as the selector
Browsers natively support the getElementByID method on their own. This means that assigning jQuery resources by their ID is a faster way of selecting them than by using another method, such as assigning things by Class, which takes more time because the selector has to traverse the DOM before completing the command.

Use the promises interface
This piece of advice is more about writing quality code than it is specifically about increasing mechanical performance. It’s kind of a tricky subject because Javascript and jQuery are very flexible, which means that there aren’t really any hard and fast rules to play by, which can result in messy code, sometimes. One thing you can do to improve the quality of your code is use the promises interface, which is design to structure and organize jQuery code specifically.

Cache objects before using them
Caching objects is really important, especially if you’re using them more than once. When an element is cached, it’s easily accessible by the command structure, and you won’t need to worry about it being called slowly. Once it’s cached, the DOM knows exactly where to look for that element, and it’ll speed up the process as a result.

Only use ready events when needed
Make sure to use the ready function sparingly. Overusing it can really eat through a lot of processing speed because it’ll keep objects readied and using memory space while waiting to fire. A better way to structure these commands is for it ready once the DOM is loaded, which will cut down on processor use.

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Use tags before classes
Once again, classes are an inefficient way to call procedures in Javascript. As mentioned above, there are alternative methods to using them. One of these is to use tags, which are created through the getElementsByTagName() command. It’s worth noting that using ID is faster, but tags are also a lot quicker than classes.

Utilize chainingUtilize chaining

If you’re referencing the selector many times in a row, there’s a better method of doing that. Using a chaining command can aggregate similar commands into a single line, which is much more elegant and a whole lot cleaner in your codebase. It also speeds up the command because each line would have to traverse the DOM individually, rather than all at once.

Give selectors a context
This goes along with what we’ve been talking about with using ID and tags over class. All of these methods, however, traverse the DOM. Something you can do is to use your selectors in such a way that they avoid the DOM and instead focus on a specific region that you know they need to access.

Data storage considerations
To go along with our discussion of the DOM, avoid storing data in the DOM itself. Storing the information in jQuery is usually a preferable option because it lets you associate the data you need with the element it relates to, which speeds up processes drawing from either of them.

Lazy loadingLazy loading

Lazy loading is a feature included with jQuery. It lets you specify what content to load at a given time in a given process. This saves a lot of time and energy, for obvious reasons. Make sure to include the jquery.lazyload.js file in your project if you want to use it.

Use group queries
Along with chaining, which we talked about a little earlier, you can use group queries to compress code that would normally be in multiple lines down to one. It saves space, it saves time, and it results in nice, clean code.
Preload images
The final piece of advice we’ll talk about here is to preload images. This can really speed up loading times because, instead of downloading an image as it’s selected, the image is already loaded up and ready to be viewed before the access command is given. Obviously, it’s not something you want to overuse, but it’s definitely quicker than re-downloading an image every single time.

Hopefully, these tips have given you a better idea about some of the finer points of using jQuery.

best not to leave it to chance!


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