gistfile1.txt

> const x = new Error();
undefined
> const vm = require('vm');
undefined
> vm.runInNewContext;
[Function: runInNewContext]
> vm.runInNewContext('x instanceof Error');
Thrown:
evalmachine.<anonymous>:1
x instanceof Error
^

ReferenceError: x is not defined
    at evalmachine.<anonymous>:1:1
    at Script.runInContext (vm.js:137:20)
    at Script.runInNewContext (vm.js:143:17)
    at Object.runInNewContext (vm.js:309:38)
    at repl:1:4
    at Script.runInThisContext (vm.js:126:20)
    at REPLServer.defaultEval (repl.js:384:29)
    at bound (domain.js:420:14)
    at REPLServer.runBound [as eval] (domain.js:433:12)
    at REPLServer.onLine (repl.js:700:10)
> vm.runInNewContext('x instanceof Error', {x});
false
>