The State of ES5 on the Web

In a recent analysis, Philip Walton discusses the current state of ES5 on the web, highlighting significant changes since 2017 when he first addressed the deployment of ES6+ code without transpiling to ES5. While many web developers have adopted this approach, JavaScript library authors remain constrained due to the need for compatibility across various deployment environments. The discontinuation of support for IE 11 in 2022 has allowed many businesses to move away from ES5, yet a substantial portion of popular websites still deploy code that is transpiled to ES5, often resulting in unnecessary bloat. Walton emphasizes that while there is nothing inherently wrong with ES5, the practice of transpiling modern code to ES5 can lead to excessive polyfills and larger bundle sizes. His findings reveal that 89% of the top 10,000 websites serve untranspiled ES6+ syntax, indicating a shift in the landscape where supporting legacy browsers is becoming less critical. He recommends that library authors reconsider the need to transpile to ES5, as the majority of sites are already using ES6+ syntax. The article concludes with a call for better configurations in build tools to avoid unnecessary code bloat and improve performance.

- The discontinuation of IE 11 support has shifted the need for ES5 compatibility.

- A significant number of popular websites are serving untranspiled ES6+ syntax.

- Transpiling modern code to ES5 can lead to excessive polyfills and larger bundle sizes.

- Library authors are encouraged to stop transpiling to ES5 as most sites are using ES6+.

- Improved configurations in build tools are necessary to reduce unnecessary code bloat.