REPL: {} instanceof Object === false with nodejs 11 and nodejs 12

With the given file:

console.js

const repl = require('repl');
repl.start('> ');

Then running in nodejs 11 & 12:

$ node console.js

> console.log({} instanceof Object)
false

But running with nodejs 10:

$ node console.js

> console.log({} instanceof Object)
true

I am expecting to be true in all cases, did I miss something?

@BridgeAR

It's caused by this code:

node/lib/repl.js

Lines 877 to 880 in 5b8df5e

    
           for (const name of Object.getOwnPropertyNames(global)) { 
        
             Object.defineProperty(context, name, 
        
                                   Object.getOwnPropertyDescriptor(global, name)); 
        
           }

That copies the Object from the main context to the REPL context.

I'm not completely sure what commit introduced this but cc @BridgeAR since you were the last one to touch that code. :-)

Workaround until it's fixed: repl.start({ prompt: '> ', useGlobal: true })

@bnoordhuis

Hi @bnoordhuis, thank you for the workaround.

With some more experiments, I can reproduce on nodejs 10 the bug with this piece of code:

const repl = require('repl');

function test(obj) {
  return obj instanceof Object;
}

repl.start('> ').context.test = test;

$ node console.js

> test({})
false

But with { useGlobal: true } it does work correctly:

const repl = require('repl');

function test(obj) {
  return obj instanceof Object;
}

repl.start({prompt: '> ', useGlobal: true}).context.test = test;

$ node console.js

> test({})
true

@BridgeAR

Maybe this bug is related to e3055dc?
cc @BridgeAR.

repl: fix some repl context issues

Please ignore this msg (#1)

Closed since it was already fixed via #28561.

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REPL: `{} instanceof Object === false` with nodejs 11 and nodejs 12 #27859

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	for (const name of Object.getOwnPropertyNames(global)) {
	Object.defineProperty(context, name,
	Object.getOwnPropertyDescriptor(global, name));
	}

REPL: {} instanceof Object === false with nodejs 11 and nodejs 12 #27859

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bnoordhuis commented on May 24, 2019

iam4x commented on May 24, 2019

starkwang commented on May 29, 2019

ZYSzys commented on Dec 9, 2019

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REPL: `{} instanceof Object === false` with nodejs 11 and nodejs 12 #27859