js-type-descriptor

Allows types to be described with JavaScript, and computes TypeScript types from those descriptions. Can be used to validate the structure of an object, or anything else where type information is required in the runtime.

Usage no npm install needed!

<script type="module">
  import jsTypeDescriptor from 'https://cdn.skypack.dev/js-type-descriptor';
</script>

README

Type Descriptor

Allows types to be described with JavaScript, and computes TypeScript types from those descriptions. Can be used to validate the structure of an object, or anything else where type information is required in the runtime.

Usage

npm i js-type-descriptor

const {isType} = require('js-type-descriptor');

if (isType(value, {kind: 'string'} as const)) {
  // value is a string
}

Types

  • "string"
  • "number"
  • "boolean"
  • "null"
  • "undefined"
  • "symbol"
  • "bigint"
  • "any"
  • "enum"
    • values Array of allowed values
  • "array"
    • subtype Type of the items in the array
  • "literal"
    • value The value of the literal
  • "intersection"
    • type1 Type
    • type2 Type
  • "union"
    • type1 Type
    • type2 Type
  • "instanceof"
    • value constructor to use in the instanceof comparison
  • "object"
    • properties A plain object with string keys and Type values