// console.log(typeof '1');
// console.log(typeof 12);
// console.log(typeof false);
var a;
var g =12;
console.log(typeof a);
// console.log(typeof null); //object
let b = {
    name:"图图"
}
let c = [1,2,3]
function fn1() {
    return 12;
}

// console.log(typeof b);
// console.log(typeof c);
// console.log(typeof fn1);

// console.log(b instanceof Object);
// console.log(c instanceof Object);
// console.log(fn1 instanceof Function);


// console.log(Object.prototype.toString.call(1))
// console.log(Object.prototype.toString.call('12'))
// console.log(Object.prototype.toString.call(true))
// console.log(Object.prototype.toString.call(a))
// console.log(Object.prototype.toString.call(b))
// console.log(Object.prototype.toString.call(c))
// console.log(Object.prototype.toString.call(fn1))
// console.log(Object.prototype.toString.call(null))

console.log(false.constructor === String)
console.log('12'.constructor === String)
console.log((1).constructor === Number)
console.log(b.constructor === Object)
console.log(c.constructor === Array)
console.log(fn1.constructor === Function)
// console.log(a.constructor === undefined)
// console.log(null.constructor === Null)