skema provides a handy and composable way to validate/transform JavaScript variables:

• Supports both async and sync flows. Skema has two working modes to support either async or sync validators, setters, etc, making it capable with much more complicated challenges.

• NOT only type checker. Unlike TypeScript, joi, and many others, Skema is not only a JavaScript type checker, but also a good solution for your Anti-Corruption Layer (ACL) to transform and purify the input data. And Skema could also be configured as a simple schema validator too.

• Pluggable basic types. Even basic types such as Number could also be replaced and customized if using Skema. Actually, in the core of Skema, there is NOT a single definition of one type.

• Powerful custom types. Every single type is able to be customized that you can handle almost everything including descriptor, conditions, default values, validators and so on.

• Composable structures. You could build a much bigger schema with the small ones into the whole world.

npm i skema

🔬 Live Demo with JsFiddle

import {shape} from 'skema'

// Schema definitions are ONLY objects.
const User = shape({
  id: 'number?',
  name: String
})

// Then use these definitions to purify our data.
const user = User.from({
  id: '1',
  name: 'Steve'
})

console.log(user)
// {
//   id: 1,
//   name: 'Steve'
// }

user.id = 'boooom!'
// throw TypeError
// - message: 'not a number'
// - code: 'VALIDATION_FAILS'

• API References
  • APIs
  • Builtin Types and How to Change Them
• Shape Definition
• Working Mode: Sync or Async
• Assign a Property after from()
• Error Handling
• Contributing

• Shape Definition
  • Purify an Object Against a Shape🔬
  • Default Value of a Property🔬
  • Optional Properties🔬
  • Skip Processing a Property🔬
  • Properties Descriptors: Non-Enumerable Properties, ...🔬
• Type Definition
  • Basic Validation | Live Demo🔬
  • Async Validation | Live Demo🔬
  • Multiple Validators
  • Basic Usage of Setters
  • Inherit Another Type
  • Declare a Type Alias to Make a Shortcut (Live Demo🔬)
  • Use Skema as the Strict Type Checker | Live Demo🔬
• Errors🔬

• @skema/basic The default built-in javascript types of skema.

MIT