javascript initialize to undefined or null or ""

Java script has many falsy values as I started learning. I have a program that gets values from a service and loads into an array like this:

function loadNames() {
    Global.names = // what should I use here? undefined, null, "", 0, {} or anything else
    var lnames = getLNames(); // this is doing some magic
        if ( lnames.length !== 0 ) {
            Global.names = new Array();
            for ( var i = 0; i < lnames.length; ++i)
                Global.names[i] = lnames[i];
    }
}

I want to know the right way of resetting Global.names. What is most appropriate here? In code I only want to check like if ( Global.names )

PS: I can't just take the return value into Global.names as the returned object is destroyed later. Hence, I need to do a deep copy

Thanks

Solution

Taken from JavaScript: the good parts :

"The if statement changes the flow of the program based on the value of the expression. The then block is executed if the expression is truthy. Here are the falsy values:

false
null
undefined
the empty string ''
the number 0
the number NaN "

So basically if you set your var to any of those values, you'll be able to do a if(var){...}