How to write multiple lines of code in Node REPL

Question

I would like to evaluate

var foo = \"foo\";
console.log(foo);

as a block, instead of evaluating line by line

var foo = \"f         


        

Answer 1

Node.js REPL supports blocks and is able to return the last expression from a block, so do some other console implementations (Chrome devtools console).

This may result in syntax error, this is a breaking change in Node 10.9.0. { could be a object literal, a block cannot be unambiguously evaluated as a block:

{
var foo = "foo";
console.log(foo);
}

While this can be unambiguously evaluated as a block and will return undefined:

;{
var foo = "foo";
console.log(foo);
}

Since the last expression from a block is logged, console.log isn't needed here:

;{
var foo = "foo";
foo;
}

Notice that this is block scope, so let, const and class won't leak to REPL scope, this behaviour can be desirable or not.