> For the complete documentation index, see [llms.txt](https://wkrueger.gitbook.io/typescript/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wkrueger.gitbook.io/typescript/intro/what-typescript-is-for.md). # What Typescript IS for? ## Works like a linter TypeScript is used as sort of an advanced **linter**, as it points errors in your code based on the coherence of the *data structures* present in it. I emphasize the term *linter* here because type-check errors really don't block your code from being compiled. The errors are just there to provide you hints. In order to collect those data structures, TS uses inference in your code. TS already knows a lot of type data from plain JS alone, but you can also complement those with extra **type annotations**. ## JavaScript compilation As type annotations are not understood by JS parsers, source `.ts` files must be compiled to `.js` in order to remove those. Typescript itself includes a compiler and nowadays this can also be done with Babel. The TS *language* aims to keep aligned with JS and proposals that had reached stage 3 ("surely coming to JS"). TS aims NOT to include extraneous features that are not or won't be part of JS. So, by writing TS, you are mostly writing a near future version of JS with types. As with Babel, you can then choose which target to compile (how old is the browser or node.js version you wish to support). ## Language services Language service support is a big focus and differential of TypeScript. A language service is a layer which aims to provide editor goodies like tooltips, navigations, completions, refactors, and suggestions, a dozen of small features which actually bring big improvements in developer experience. The opposite case would be a language in which you only get the compiler feedback when you save a file. As the TS team works in tandem with the VSCode team to provide its JS language service, its editor experience is very refined. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://wkrueger.gitbook.io/typescript/intro/what-typescript-is-for.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.