See http://stackoverflow.com/a/30172776/617937

hoisting.js

function works() {
    function foo() {
        console.log('ok');
    };

    var works_ref;
    works_ref = foo;

    console.log('works ' + works_ref);
}

function fails() {
    var fails_ref, foo;

    // Anonymous, so it can't actually be called with this name, but is used and referenced by the JavaScript VM or interpreter
    function unnamed_001() {
        console.log('ok');
    };

    fails_ref = foo; // <---------- note this line.
    foo = unnamed_001;

    console.log('fails ' + fails_ref);
}