I would argue that Javascript is a hybrid of pass by reference because of the case below though.

    function someFunc(v) {
      v.myvar = 456;
      v = someOtherObject;
    }

    var foo = someObject;
    foo.myvar = 123;
    someFunc(foo);
    // foo still refers to someObject
    // foo.myvar is 456

Banning our team from passing objects around except in specific, discussed, cases got rid of lots of difficult to track down bugs.