Node.js: require in REPL?

Question

Why require in REPL doesn't use cache from main context and requires file again?

Example: test.js:

var repl = require('repl');
global.a = require('./a');
repl.start({
  prompt: "node via stdin> ",
  input: process.stdin,
  output: process.stdout
});

a.js

console.log(1)

I'm starting test.js:

node test.js

It print's "1"

when i print "require('./a')" in REPL:

node via stdin> var aInREPL = require('./a')

and it prints "1" again, and so, global.a !== aInREPL

But sometimes I need to get in REPL same object as in main program (for example Singletone). How can I do this?

Answer 1

Add the required code (object, function, ..) to the REPL's context:

var repl = require('repl');
repl.start({
  prompt: "node via stdin> ",
  input: process.stdin,
  output: process.stdout
}).context.a = require('./a.js');

Now it will print 1 only once =) or add global to REPL's context

Answer 2

Out of the box the REPL runs in a different context (see repl.start function for details).

Basically, you have two options to share your global context with the newly started REPL:

• You can provide the useGlobal: true option in your call to start .
• You can attach external objects to the REPL's context property.

Which way is preferred depends on what you want to achieve: Do you want to share anything , then go with useGlobal . If you only want to share selected objects, use the context property and only assign those objects you want to share (see Scott's post for an example).