Thankfully because of the existence of resw completing the console.log debugging tool is going to be trivial. The primary entry point for resw is the Writer struct, which has a method write_part that will take a &mut self and &ProgramPart, so we can use that in our for loop to write out the parts as they are parsed. That might look like this.

use resast::prelude::*;

fn main() {
    let js = get_js().expect("Unable to get JavaScript");
    let parser = Parser::new(&js).expect("Unable to construct parser");
    let mut writer = Writer::new(::std::io::stdout());
    for part in parser.filter_map(|p| p.ok()).map(map_part) {
        writer.write_part(&part).expect("Failed to write part");
    }

With that complete we can see how well it works for us. Let's use the following example JavaScript.

function Thing(stuff) {
    this.stuff = stuff;
}
let x = new Thing('argument');

Just as a simple test we could enter the following into our terminal

$ echo "function Thing(stuff) {
    this.stuff = stuff;
}
let x = new Thing('argument');
" | console_logify
function Thing(stuff) {
    console.log('Thing', stuff);
    this.stuff = stuff;
}

let x = new Thing('argument!');

That looks exactly like the output we were looking for. Let's double check that it will behave as expected by piping the output to node

$ echo "function Thing(stuff) {
    this.stuff = stuff;
}
let x = new Thing('argument');
" | console_logify | node -
Thing argument

It worked!