Given the following code why am I getting different values for a and b? I would have thought they would return the same thing:

(function() {
    var a = $('#foo');

    var Test = function(){
    console.log(a); //outputs 'jQuery()'
    var b = $('#foo');
    console.log(b); //outputs 'jQuery(select#foo)' which is what I want
    };
})();

This question stems from me trying to stick frequently used selectors into vars. Originally I was doing it in each method (like I did with var b in the above example) but then I found I needed to use the selectors in multiple methods so I moved the assignment out to be available (or so I thought) to all of the methods in that anonymous function. As you can see, it does not work. Why is this?