• A type-system based only on inference with JavaScript code
• Incremental typing in JavaScript
• TypeScript code
• TypeScript with strict enabled

Each step represents a move towards a safer type-system, but not every project needs that level of verification.

This is when you use an editor which uses TypeScript to provide tooling like auto-complete, jump to symbol and refactoring tools like rename. The has a list of editors which have TypeScript plugins.

JSDoc annotations come before a declaration will be used to set the type of that declaration. For example:

You can find the full list of supported JSDoc patterns in JSDoc Supported Types.

If you have a lot of JavaScript files you want to add errors to then you can switch to using a . You can skip checking some files by adding a // @ts-nocheck comment to files.

TypeScript may offer you errors which you disagree with, in those cases you can ignore errors on specific lines by adding or // @ts-expect-error on the preceding line.