How to make your JavaScript more Powerful?


The Cost of JavaScript

Nowadays, developers are relying more and more upon the JavaScript for creating new programs. Every website is now running over the lucrative features of the JavaScript. So, that’s why today we are to see how with a little discipline, your website can load quickly and promptly on the mobile devices.

Well, when we are talking about the cost of JavaScript, then we are not at all referring to the monetary figures. No, the cost of JavaScript is discussed in the context of the download & execution cost. So, in this post, we will figure out different heads where we can reduce the cost of JavaScript.


  • Network


This is the most vital topic, as sending the JavaScript bytes over the wire takes more time if the network of the user is slower.  This problem occurs mainly in the developing countries, where the speed of 4G, 3G and Wi-Fi network is very poor. And, most people are stuck with the 2G network. So, by following few methods network cost of the JavaScript can be reduced:

  • Code splitting can be beneficial.
  • Magnifying the code is a nice choice.
  • Compress your code using the Brotli outperforms gzip on compression ratio.
  • Remove unused codes using different tools like DevTools code coverage, tree-shaking, Closure Compiler’s advanced optimization etc.
  • Use Service Network caching to minimize network trips.


  • Parse/Compile


So, after downloading the JavaScript website, the next cost that is most crucial is the parse and compile cost. If your JavaScript site takes more time in compiling and parsing the site for interaction, then it means that you are sending heavy JavaScript costs to your website.

The major role here is played by the smartphone you are using in receiving the JavaScript codes. According to JavaScript Start-up Performance, there is 2-5x difference can be seen in the parse/compile loading rate of the website according to the processor of the phone.

For example, if you try to open regular CNN website on high-end iPhone 8, then the parse/compile time is recorded 4s. But, if the same website is opened on the regular phone, then parse/compile time will be 13s. So, now you see the impact of parse/compile cost on your lives, people.

So, to reduce the parse/compile cost, you have to remove non-critical JavaScript from your pages which can reduce transmission times, CPU-intensive parsing & compiling and potential memory overhead. This will increase your page interaction rate also.


  • Execution Time


The execution time also increases the cost of JavaScript. JavaScript execution is one of the main thread function of loading page. The longer execution can slow down the interaction time for the users.

So, to fix this issue, you can take benefit from the JavaScript chunks, instead of locking all them up in main threads. Also, try to explore if you can reduce the work done during the execution.


  • JavaScript Delivery Cost


When you are trying to slow the network and parse/compile costs for your website, then numerous route based chunks can help you in achieving this goal. PRPL is a pattern that helps you in signifying the interaction rate through code splitting and caching.

Using the V8’s Runtime Call Stats you can examine the parse time of numerous websites and Progressive Web Apps. Wego is the live example of using PRPL, this site has improved their interaction rate and parse time. Some websites are adopting code splitting and performance budgetary techniques to reduce JavaScript cost.


  • Miscellaneous Costs


JavaScript cost can impact your page performance in plenty of other ways also, such as:

  • Memory. The webpage can jam or pause frequently due to the Garage Collection. When a browser reclaims memory, JS execution is paused so a browser frequently collecting garbage can pause execution more frequently than we may like. To avoid this problem, regularly keep eye on the memory leaks and garbage collections.
  • Blockage. JavaScript can block the main threads because of the unresponsive pages. So, in that case, chunk up your work into smaller pieces to keep the page responsive. For that you can use requestAnimationFrame() or requestIdleCallback() for scheduling.

Final Remarks

Transmission size and parse time are important for CPU bounds. Keep your cost low to fully optimize your JavaScript website. So, folks, if you are designing a mobile based website, then do representative hardware, keep your JavaScript cost low and adopt the performance budget so that your team can keep eye on the website.

P.S- That’s why to keep your JavaScript costs in check and make them as low as possible.

About the author

Arpit Agarwal

I am a freelancer content writer, web developer and Video editor who loves to write technical stuff and on the other hand makes awesome videos as well. I like to make people happy with my writing and also try to make sure, you come back to read more.

By Arpit Agarwal

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