Embracing gradual typing

How to gradually adopt TypeScript in a large existing JavaScript project effectively? That's the topic for this talk.

The talk is in Thai language (English subtitles available and slides are all in English). This was my first prerecorded talk for TS BKK Meetup. Since this talk is prerecorded, it contains a plenty of coding demos.

Adopting TypeScript in a large existing project may not be that straightforward:

• Hundreds if not thousands of existing untyped JS files.
• Not sure if benefits would outweigh the costs ("the TypeScript tax").
• Changes may be met with friction in a large team.
• You or your team do not want to introduce any extra build step.

Topics including:

• How you may already be using TypeScript in your JavaScript project.
• TypeScript the language, the compiler, and the language service.
• Using JSDoc to improve type inference, code completions, and IntelliSense.
• Configuring jsconfig.json for improved code actions and automatic refactoring.
• Using // @ts-check to type-check JavaScript files (with examples on dealing with a few type-checking errors).
• Enabling checkJs to type-check JavaScript files project-wide.
• Creating a .d.ts file next to a JavaScript file to keep the .js file unmodified.
• Creating a global .d.ts file to declare modules and global variables.
• Discussion on strategies for improving developer productivity, improving code documentation, and reducing chance of runtime errors.