Node.js console.log（object）打印空对象

Question

I'm curious about the way Node.js prints objects through console.log(object).

I have the following code (from Learning Javascript Design Patterns book) under a file constructor.js

var defineProp = function(obj, key, value){
    var config = {
        value: value, 
        writable: true,
        configurable: true
    };
    Object.defineProperty(obj, key, config ); 
}

var person = Object.create(Object.prototype);


defineProp(person, "car", "Delorean"); 
defineProp(person, "dateOfBirth", "1981"); 
defineProp(person, "hasBeard", false); 

console.log(person); //This prints {} in Node.js

Running with that code with >node constructor.js prints an empty object. Chrome however, prints what I would expect if I run the code inside an HTML file.

console.log(person); //Chrome prints Object {car: "Delorean", dateOfBirth: "1981", hasBeard: false} 

Note: I can still print the attributes (such as console.log(person.car) ) under Node, just not the object itself (such as console.log(person) )

Why is this? Do Chrome and Node use separate prototypes for the console object, even though they share the same javascript engine?

Answer 1

console.log() in node utilizes util.inspect() , which uses Object.keys() on objects, which returns only own enumerable properties . Also, by default , Object.defineProperty() sets enumerable: false if you do not explicitly set it to true .