• undefined
• null

undefined

let x;
undefined
typeof x
"undefined"
let y= 111;
typeof y
"number"
typeof yy
"undefined"

null

let x=55;
x;
55
let y=null;
y;
x+y;
55
x*y;
0
if (!y) console.log("false");
false
if (y) console.log("false");
let z=Boolean(true);
typeof(z);
"boolean"
z==true
true
z===true
true
z==false
false
```