Background. Using JavaScript frameworks has become a popular approach for developing web applications. However, the large bundle sizes associated with framework usage may not always be necessary from a sustainability standpoint. Utilizing a framework or not could potentially impact a web application’s performance and carbon emissions. 

Objectives. This study aims to identify sustainable approaches to frontend web development and investigate whether a comparable difference in performance, energy consumption, and carbon emissions exists between applications built using a framework like React.js versus those developed using vanilla JavaScript. 

Methods. A literature review was conducted to identify important factors for creating sustainable web applications from previously published materials. An empirical study was performed where two test applications were created; one developed in vanilla JavaScript and one using the React.js framework. Experiments on these prototypes compared performance and estimated carbon emissions on the applied technologies. 

Results. When researching literature published on sustainability within web development, the factor most frequently mentioned was web performance optimization. The results of the empirical study found that the application written in vanilla JavaScript achieved higher performance metrics and lower estimated carbon emissions than the prototype developed with React.js. 

Conclusions. This thesis has found that web performance optimization is an important, powerful, and easy-to-use approach for achieving more sustainable web applications. This study has found several important factors for creating sustainable web applications, which can significantly impact an application’s carbon emissions. The study found that the best-performing test application achieved the lowest estimated carbon footprint. This thesis recommends that developers make informed decisions and consider sustainability when choosing a development strategy, like using a framework or not for future projects.