Right:

var keys = ['foo', 'bar'];
var values = [23, 42];

var object = {};
while (items.length) {
  var key = keys.pop();
  object[key] = values.pop();
}
Wrong:

var keys = ['foo', 'bar'],
    values = [23, 42],
    object = {},
    key;

while (items.length) {
  key = keys.pop();
  object[key] = values.pop();
}