ESInfer – Make JavaScript Type-Safe
Hello, folks. I'm Jiang, the author of ESInfer. I love writing Javascript because it has a prosperous ecosystem and is quick to get my hands dirty. However, sometimes it's painful when the flow is not fast to follow due to the lack of a type system. To solve this, I wrote ESInfer, a statical inference tool, to automatically type check and generate type annotations for Javascript. It works with pure Javascript without any add-ons to the language or user-space code and supports highly dynamic features, such as the modification of prototypes. It is still in the very early stage, which offers…
ESInfer – Make JavaScript Type-Safe launched on October 15, 2022 with 83 votes, #518 of 3,153 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 4 years on.
In plain words
ESInfer is a static analysis tool that automatically type checks and generates type annotations for JavaScript code. It works with pure JavaScript without requiring language extensions or code modifications, and supports dynamic features like prototype manipulation. The tool currently covers ES5 and selected ES6 features, with ongoing development to expand ES6+ support. It is designed for JavaScript developers who want type safety without manually writing type annotations.
written from the facts on this page · September 2026
From the sources
Make javascript type-safe
Let's say there are THREE layers out of there. #1. Source of the truth That is your pure Javascript code. #2. Type Check & Type Generation ESInfer stands here. It will take all the assumptions your code made to see if there are any conflicts. If all pass, you get the type information. #3. Applications You got the information of types. Then the only way to limit yourself to doing something is only the imagination. Examples can be listed, but not limited to: * Communicate with the editor's LSP to give tips on types(this website:ESInfer.com is doing this way) or code suggestions. * Better linting * Annotation generation for or not for typescript/flow * Statical analysis integrated into your…from esinfer.com
In the maker’s words, at launch
Hello, folks. I'm Jiang, the author of ESInfer. I love writing Javascript because it has a prosperous ecosystem and is quick to get my hands dirty. However, sometimes it's painful when the flow is not fast to follow due to the lack of a type system. To solve this, I wrote ESInfer, a statical inference tool, to…
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