Svelte.js or Svelte is a UI framework or tool used for building fast web applications. It is very similar to JavaScript frameworks such as React and Vue, which make it easy to build slick interactive user interfaces. It is also used to solve the same problems for which React or Vue are used, but Svelte.js facilitates users to build applications in a declarative, component-driven way rather than to create an imperative DOM manipulation.
The most crucial difference between Svelte and other JavaScript frameworks such as React and Vue is that it converts our app into ideal JavaScript at build time, rather than interpreting our application code at run time. This provides a great advantage: we don't have to pay the performance cost of the framework's abstractions, and it doesn't cost a penalty when our app first loads. That's why it provides faster loading and faster running apps.