brain teaser

var a = [{ foo: 'bar' }];

var method = function (arr) {

    var local = arr.slice();

    console.log(local === arr); 

    local.forEach(function (obj) {
        console.log(coll === arr);
        obj.wtf = true;
    });
};

method(a);
console.log(a);  // How did "wtf" get here?