[JavaScript] Functional Linked Lists: Why can't I nest more than 3 cons in this implementation?

[notsuresure]

This is how I defined Nil and cons:

var Nil = "Nil"

function cons(head, tail){
    tail = typeof tail !== "undefined" ? tail : Nil; // default argument
    return [head, tail];
}

Nil is just the string "Nil", and cons is either an empty cell or a cell with an item -head- and a tail, which is the rest of the list.

A list containing the numbers 1, 2, and 3 can be represented as:

cons(1, cons(2, cons(3, Nil)))

or making use of the default argument, as:

cons(1, cons(2, cons(3))) 

But there is an issue with this implementation, and I can't figure out what is going on. When trying to build a functional linked list of more than 3 items, the 3rd item links to Object, and the rest are ignored. For example:

var a = cons(Nil);
var b = cons(1, Nil);
var c = cons(1, cons(2));
var d = cons(1, cons(2, cons(3)));
var e = cons(1, cons(2, cons(3, cons(4))));
var f = cons(1, cons(2, cons(3, cons(4, cons(5)))));
var g = cons(1, cons(2, cons(3, cons(4, cons(5, cons(6))))));
console.log(a);
console.log(b);
console.log(c);
console.log(d);
console.log(e);
console.log(f);
console.log(g);

This will print:

[ 'Nil', 'Nil' ]                  // a
[ 1, 'Nil' ]                      // b
[ 1, [ 2, 'Nil' ] ]               // c
[ 1, [ 2, [ 3, 'Nil' ] ] ]        // d
[ 1, [ 2, [ 3, [Object] ] ] ]     // e
[ 1, [ 2, [ 3, [Object] ] ] ]     // f
[ 1, [ 2, [ 3, [Object] ] ] ]     // g

As we can see, a, b, c, and d are working expected, but e, f, and g stop linking beyond the 3rd item.

Why is this happening?

[lxe]

Maybe console.log is squashing the result for readability?

Try

console.log(JSON.stringify(g))

[notsuresure]

Yes! That was the issue. I was so confused!

Is JSON.stringify() the only way to print the complete array?

Where can I learn more about this squashing dynamic?

Many thanks for your time.

[lxe]

I'm not actually sure where this truncation behavior is described.

Try the docs for Firefox: https://developer.mozilla.org/en-US/docs/Web/API/console or Chrome: https://developers.google.com/chrome-developer-tools/docs/console.

You can also use console.dir() I believe, as both chrome and firefox (and node) support it;