6.js

var a=10;
var b=20;

var c;
c = a;
a = b;
b = c;

console.log(a,b);

var e=10;
var f=20;

e = e+ f;
f = e-f;
e = e-f;
console.log(e,f);

var g=10;
var h=20;
[g,h] = [h,g]
console.log(g,h);

let w = 100;