JavaScript: Is my 'isNullOrEmpty' function a good one?
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I am using this code to test if an object is null or empty:

    var isNullOrEmpty = function(obj) {
        // this should handle if someone defines a variable named 'undefined'. 
        if(obj == null || typeof(obj) == 'undefined' || obj == "") {
            return true;
        }
    
        return false;
    }

Is there anything I'm missing?

Thanks.