type-checking

Runtime type checking and type assertion library for Node and the browser

• Traditional syntax.
• Aims to cover every EcmaScript language type and specification type except Proxy.
• Offers a small set of composable numeric predicates and assertions for integers, signed numbers, and special numbers.
• Cross-realm/iframe support (i.e., predicates should remain correct across different realms).
• Does not get easily fooled by the value of the Symbol.toStringTag property.
• Handles -0 and NaN correctly.
• Aims to provide readable error messages.
• Does not rely on Symbol.toStringTag
• You can easily disable typeChecking.assert() (but not .expect()) for production: in Node: by setting the NODE_NDEBUG environment variable; in Nashorn: by setting the "nashorn.ndebug" system property.
• Does not aim to cover any DOM API type.
• Does not aim to cover complex constrained string types like email address etc.
• Does not aim to offer custom type constructor.

Installation

npm install @fmartin5/type-checking

Usage

const tc = require("@fmartin5/type-checking");

let x = 0;

tc.isNumber(x); // true
tc.isInteger(x); // true

tc.isPositiveNumber(x); // true
tc.isPositiveInteger(x); // true

tc.isStrictlyPositiveNumber(x); // false
tc.isStrictlyPositiveInteger(x); // false


let map = new Map();
tc.isMap(map); // true
tc.isWeakMap(map); // false

tc.expectMap(map); //
tc.expectWeakMap(map); // TypeError: expected a 'WeaMap' object.

Tests

Clone the repo, then do:

npm install
npm test

License

AGPL-3.0