typr

0.2.1 • Public • Published

typr

npm status build status dependency status coverage status locked

Mutually Exclusive JS Type Testring

The aim of this module is to completely partition the set of JS objects into a set of types T:

T = [Function, Object, Date, Number, String, Boolean, RegExp, Undefined, Arguments, Null, Array]

Prop. 1 For every JS object x, x has exactly one type in T where [typr] returns true for its typecheck.

Prop. 2 Whether or not an Object has keys and can be looped over is determined by t.hasKeys and is completely independent of the type found in prop 1.

Prop. 3 Number types can be partitioned into 3 sub-types:

  • isNaN
  • isInfinite
  • isNumeric i.e. !isNaN && !isInfinite

These properties are tested extensively.

Usage

Basic usage:

var typr = require('typr');
typr.isFunction(el); // true iff el is a function

Read the very short API.

Object Keys

The reason for prop 2 is that Objects can masquerade othes instances like Functions, Strings, RegExps, Dates. Object.keys() (and for-in) will actually work on some of these. This does not mean they will have interesting keys, but they sometimes do!

A common trick in node modules to export a function, but additionally attach properties to it. Such an object will only be a Function by our partitioning (as that was its original construction), but it is Object-like.

If you would rather test for enumerability of properties, use the extra test for Object-likeness: hasKeys.

Note again that this may not be super intuitive:

var dualThing = new String("wee");
dualThing.prop = "hi";
Object.keys(dualThing); // [ '0', '1', '2', 'prop' ]
 
t.isObject(dualThing); // false
t.isString(dualThing); // true
t.hasKeys(dualThing); // true

Installation

$ npm install typr

Running tests

Install development dependencies

$ npm install

Run the tests

$ npm test

License

MIT-Licensed. See LICENSE file for details.

Readme

Keywords

none

Package Sidebar

Install

npm i typr

Weekly Downloads

14

Version

0.2.1

License

MIT

Last publish

Collaborators

  • clux