Less type boilerplate, more fun!
The functions available were written as needed over the course of two years (2015-2017), and with most browsers' support in mind - not guaranteed to properly work in IE8 or below without performance hitches or such.
var stu = require('stringularity-type-utils');
stu.isString('someString');
// ...The unit tests were written using mocha, chai and coverage with istanbul, and nyc. A lot of effort went into the exhaustive unit testing of the fundamental functions - the basics.