>>>>>I tested using both positive and negative priority and your directive always ran first. I *did* get it to work by changing your formatter to:

>>>>>                    function bind() {
>>>>>                        return ngModel.$formatters.unshift(function (value) {
>>>>>                            return format(value);
>>>>>                        });
>>>>>                    }

Don't know why the priority approach didn't work but this shows that your formatter needs to be first in the $formatters array.....
>>>>
>>>>There is some activity in the issue I raised
>>>>
>>>>https://github.com/angular/angular.js/issues/11157#issuecomment-75706528
>>>>
>>>>and I also posted a new plnkr
>>>>
>>>>http://plnkr.co/edit/z1BWMoPmnsCZlAUra0os?p=preview
>>>
>>>Using Priority and push gives exactly the same formatter execution order (ie angulars directive followed by yours). Behaviour is the same in both cases.
>>>What exactly is your problem with this code ?
>>>BTW you should probably also add 'event.preventDefault()' in your keydown event handler - simply returning true/false only works in IE.
>>>
>>>Also you need to prevent multiple decimal points:

if (isDecimal(event.keyCode)) {
>>>                          if (event.srcElement.value.indexOf('.') !== -1) {
>>>                              event.preventDefault();
>>>                              return false;
>>>                          }
>>>                      }

(or use a regex)
>>
>>Thanks, I'll make adjustements.
>
>But you didn't answer my question: "What exactly is your problem with this code ?"

I was seeing the error that I posted in the issue, but I do not seem to reproduce it in that plnkr. Also, I do not see the number formatted with , e.g. I thought the idea of the directive was to nicely format the number to be 890,900.00 (e.g. with commas), but I do not see that in the directive's code or the output.