JavaScript: Check to see if object exists

JavaScript: Check to see if object exists

I have a function to return if a variable/object is set or not:
function isset() {
var a = arguments, l = a.length;
if (l === 0) { console.log("Error: isset() is empty"); }
for (var i=0; i<l; i++) {
try {
if (typeof a[i] === "object") {
var j=0;
for (var obj in a[i]) { j++; }
if (j>0) { return true; }
else { return false; }
}
else if (a[i] === undefined || a[i] === null) { return false; }
}
catch(e) {
if (e.name === "ReferenceError") { return false; }
}
}
return true;
}
For example, this works:
var foo;
isset(foo); // Returns false
foo = "bar";
isset(foo); // Returns true
foo = {};
isset(foo); // Returns false
isset(foo.bar); // Returns false
foo = { bar: "test" };
isset(foo); // Returns true
isset(foo.bar); // Returns true
Here is the problem... if foo is never set to begin with, this happens:
// foo has not been defined yet
isset(foo); // Returns "ReferenceError: foo is not defined"
I thought I could use try/catch/finally to return false if error.name ===
"ReferenceError" but it isn't working. Where am I going wrong?