How can we incrementally execute code 1 line at a 1 time?

We have a code block. We'd like to have swift-playground like result where we see the result of each expression in the right rail...

Approaches I've tried

Eval each line separately

Doesn't work because each line sets up a new in-browser VM with isolated execution context (lose the scope from prior lines).

Eval incrementally

Eval to line 1, eval to line 2, eval to line 3 etc...

Doesn't work because the last expression is what's returned...

ie:

This returns 5. What I'm looking for is 3 returns: undefined, 5, undefined. Instead the last line returns 5. :(

eval(`
	let x;
	x=5;
	let y;
`')

This is because of statement vs expression.

SOLUTION!!!!: Nested eval.

eval(`	let x;
	x=5;
	eval('let y'); // expression that returns a value`')

Eval and pass in execution context

TODO: Make a til on execution context...

Q: Could we pass in / provide the scope by doing module wrapping like node does?

I believe this is how Webpack and node handle module isolation...

// wrapper
function(){

	code we want to run


}(); // execute immediately

// we could just use the params and args to define the local scope right...? interesting...

//and then if we replace window, or run web worker we could pass in the scope and isolate it?

Q: Could we define the execution context that way? Interesting......