$ npm install --save assertrue

const assert = require('assertrue');

assert.isTrue(true); //ok
assert.isTrue(1); //ok
assert.isTrue('a'); //ok
assert.isTrue(false); //AssertionError
assert.isTrue(0); //AssertionError
assert.isTrue(''); //AssertionError

assert.isStrictTrue(true); //ok
assert.isStrictTrue(1); //AssertionError
assert.isStrictTrue('a'); //AssertionError
assert.isStrictTrue(false); //AssertionError
assert.isStrictTrue(0); //AssertionError
assert.isStrictTrue(''); //AssertionError

assert.isNaN(NaN); //ok
assert.isNaN('a'); //ok
assert.isNaN({}); //ok
assert.isNaN(1); //AssertionError
assert.isNaN('1'); //AssertionError
assert.isNaN(true); //AssertionError

assert.isStrictNaN(NaN); //ok
assert.isStrictNaN('a'); //AssertionError
assert.isStrictNaN({}); //AssertionError
assert.isStrictNaN(1); //AssertionError
assert.isStrictNaN('1'); //AssertionError
assert.isStrictNaN(true); //AssertionError

assert.isStrictString('a'); //ok

assert.isStrictString(['a']); //ok

assert.isStrictFunction(()=>{}); //ok

assert.isStrictRegExp(/\w+/ig); //ok

assert.isStrictBoolean(true); //ok

assert.isStrictNumber(1); //ok

assert.is(1, Number); //ok
assert.is(1, 'Number'); //ok

class Super {}
class Sub extends Super {}

assert.is(new Sub(), Sub); //ok
assert.is(new Sub(), Super); //ok
assert.is(new Super(), Super); //ok
assert.is(new Super(), Sub); //AssertionError
assert.is(new Sub(), 'Super'); //AssertionError

class Super {}
class Sub extends Super {}

assert.isAssignableFrom(Super, Sub); //ok
assert.isAssignableFrom(Super, Super); //ok
assert.isAssignableFrom(Sub, Sub); //ok
assert.isAssignableFrom(Sub, Super); //AssertionError

class Super {}
class Sub extends Super {}

assert.isAssignableFrom(Sub, Super); //ok
assert.isAssignableFrom(Super, Super); //ok
assert.isAssignableFrom(Sub, Sub); //ok
assert.isAssignableFrom(Super, Sub); //AssertionError