Classic value test. Shallow, not checking type nor diving into prototype.

classic-value-test[shallow].js

// https://codesandbox.io/s/ykmo8wp63v

const isNull = null;
const isNullNumber = 0;
const isUndefined = undefined;
const isEmptyString = '';
const isNegativeNumber = -1;
const isEmptyArray = []; // shallow test
const isEmptyObject = {}; // shallow test
const isUndefinedString = 'undefined';
const isDefinedNumber = 42;

const testValue = v => v ? 'yup' : 'nope';

console.log(testValue(isNull)); // nope
console.log(testValue(isNullNumber)); // nope
console.log(testValue(isUndefined)); // nope
console.log(testValue(isEmptyString)); // nope
console.log(testValue(isNegativeNumber)); // yup
console.log(testValue(isEmptyArray)); // yup
console.log(testValue(isEmptyObject)); // yup
console.log(testValue(isUndefinedString)); // yup
console.log(testValue(isDefinedNumber)); // yup