TypeScript & runtime type-checking, simple solution in 2020 [closed]

Answer 1

I don't know any cool tool to do that automatically but I can tell you what I use to validate types on runtime: AJV - https://github.com/ajv-validator/ajv

It's not ideal because you need to generate your json schemas for each type, but you can automate that with typescript-json-schema (https://github.com/YousefED/typescript-json-schema#readme)

Hope this helps!

Answer 2

I'm using io-ts. You only need to write once for type and runtime checking.

Answer 3

Typescript's instanceof type guard checks the constructor function, but I don't think it checks all the keys as well. Still, in most cases, it should be enough.

Working with external API, you can use class-validator package for more detailed validation, and class-transformer-validator if you want to transform plain objects (for example, parsed from JSON) to your classes.

Answer 4

TySheMo https://github.com/tangshuang/tyshemo

A javascript runtime data type checking system ...

I have been using this library for front-end api guarding

Sometimes back-end gives me a null or an empty object {} breaking down the page with ... cannot read property xxx of null ...

Write an interceptor for api's responses using this, you can capture the dirty data no matter how deep the data structure of res is

Personally, I have revised the source code of TySheMo and it really is a great piece of work

Answer 5

Give typescript-runtime-types a try. I don't know how or if this works with Babel, but there is a small section on using it with Webpack and awesome-typescript-loader. I think it does what you're looking for, although the only examples it shows are with interfaces, which may mean you aren't allowed to nest types or use & or | or Pick or other complex type annotations. If that's true, you will just need to use io-ts.

Answer 6

I was frustrated by this as well and ended up writing my own type guard generator called ‛ts-type-checked‛ available as an NPM module. It is a TypeScript transform that generates type guards based on your types.