node-repl

an interactive repl for debugging node programs.

run a node program but also attach a repl to the same context that your code runs in so you can inspect + mess with stuff as your program is running

available as a command-line tool

currently this only works on node >=0.12 and iojs as it uses a generator to make the eval loop preserve scope.

installation

npm install node-repl -g

$ node-repl
Usage: node-repl <filename>
 
$ node-repl your-program.js
>

suppose we have a program called hello.js that has these contents:

var pizza = 1

if you run node-repl hello.js you will get a repl, just like when you run node.

The difference is that this repl is running in the same context as your program.

$ node-repl hello.js
> 1 + 1 // we are in a node repl
2
> pizza // we can access variables in our program
1
>