Javascript trivia: check for equality against the empty object

Question

Probably a duplicate of this question.

Silly javascript question: I want to check if an object is the emtpy object.

I call empty object the object that results from using the empty object literal, as in:

 var o = {};

As expected, neither == nor === work, as the two following statements

 alert({}=={});
 alert({}==={});

give false.

Examples of expressions that do not evaluate to the empty object:

• 0
• ""
• {a:"b"}
• []
• new function(){}

So what is the shortest way to evaluate for the empty object?

Answer 1

function isEmpty(o){
    for(var i in o){
        if(o.hasOwnProperty(i)){
            return false;
        }
    }
    return true;
}

Answer 2

You can also use Object.keys() to test if an object is "empty":

if (Object.keys(obj).length === 0) {
  // "empty" object
} else {
  // not empty
}