SOURCE

const foo = function(){
    return ("test")
}
let a = {a:2}
let b =2
let c = ("c")
let d = ({d:"d"})
console.log(Object.prototype.toString.call(foo))
console.log(typeof foo())
console.log(Object.prototype.toString.call(a))
console.log(Object.prototype.toString.call(b))
console.log(Object.prototype.constructor.call(b))
console.log(Object.prototype.toString.call(c))
console.log(c)
console.log(typeof c)
console.log(c instanceof String)
console.log(typeof d)