fixed_typeof.js

function getType(obj) {
    const signature = Object.prototype.toString.call(obj);
    return signature.slice(8,-1).toLowerCase();
}

const cases = [
    // undefined
    undefined,

    // null
    null,

    // Boolean
    false,
    true,

    // Number
    NaN,
    Infinity,
    -Infinity,
    -0,
    -1,

    // String
    '',

    // Symbol
    Symbol('sym'),

    // Object
    (function(){}),
    [],
    {},
];

for (const val of cases) {
    const typeName = getType(val);
    typeName === 'string' 
        ? console.log('%s\t"%s"', typeName, val)
        : console.log('%s\t%s', typeName, val)
    ;
}