Netizen 4e6 visualized the statistics of the mozilla/gecko-dev library in March 2022 and found that the Rust programming language born in Mozilla accounts for only 9.9% of the Firefox browser code.
Originally launched by Mozilla, the maker of Firefox, the Rust language was developed by web leaders and the father of JavaScript, Brendan Eich, Dave Herman, and Graydon Hoare. Mozilla used it to develop the experimental rendering engine Servo, and integrated some of its CSS rendering components such as Quantum Style into the Firefox browser.
Mozilla's original plan was to completely rewrite Firefox's C++ code in Rust, replacing C++ with the more secure Rust. However, due to the epidemic, Mozilla laid off the Rust team and most of the Rust core developers in the 2020 layoffs. Then the Rust project declared its independence and created the Rust Foundation , and the Servo engine became a Linux Foundation managed project .
So Mozilla's Rust rewrite plan has also been put on hold. Today, Rust accounts for only 9.9% of Firefox's code, while C++ language accounts for 26.8%, C language accounts for 13.4%, JavaScript accounts for 27.5%, HTML accounts for 16%, Python accounts for 4.8%.