javascript assignment exploration

copyorref.js

// assignment as copy or reference?
// run in node.js as node copyorref.js

console.log('assignment by value for simple scalars')
var a = 8;
var b = a;
a++;
console.log('a: '+a + ', b (not changed): '+b);

console.log('\nassignment by reference:  aa[4]=45 is also in other vars')
var aa = [1,2,3];
var bb = aa; // reference
var x = {'aa':aa}; // this is also a ref to  aa
var y=x //ref;
aa[4]=45;

console.log('aa: '+JSON.stringify(aa))
console.log('bb: '+JSON.stringify(bb))
console.log('x: '+JSON.stringify(x))
console.log('y: '+JSON.stringify(y))

console.log('\nbut if you change aa by assignment, bb and refs in x,y don\'t change')
aa = aa.slice(1);
console.log('aa: '+JSON.stringify(aa))
console.log('bb: '+JSON.stringify(bb))
console.log('x: '+JSON.stringify(x))
console.log('y: '+JSON.stringify(y))

console.log('\nput a ref to the new aa into x and change other things, all mirrored by y (same reference)')
x.aa=aa;
x.banana = 'fruit';
y.bb = bb;
aa[4]=4;
bb[4] = 45;

console.log('aa: '+JSON.stringify(aa))
console.log('bb: '+JSON.stringify(bb))
console.log('x: '+JSON.stringify(x))
console.log('y: '+JSON.stringify(y))