Date validation using angular js

I advise you to use moment.js. Here's a basic tutorial and help to get started: https://dzone.com/articles/getting-started-with-momentjs-intro-with-examples

Basically you would do:

function testDate(startDate, endDate){
    var start =  moment(startDate, 'mm-dd-yyyy');
    var end = moment(endDate, 'mm-dd-yyyy');
    if(endDate.isBefore(start)){
       //start before end
    }
    if(startDate.add('days', 11).isAfter(endDate)){
       //end not within 10 days range
    }
    //success!
}

It would be something like that. Hope it helps!

For simple pattern matching, you can use the ngPattern directive. For more complex validation (such as ensuring it's a valid date and within a certain range of another date), you will need to write your own validation directive or use the handy custom validation directive available from Angular-UI.

https://htmlpreview.github.io/?https://github.com/angular-ui/ui-validate/master/demo/index.html

Can you provide more details about this as in what library are you using for datepicker. It would help us answer.

Since you are using a datepicker you can restrict the date range in the fromDate field do not display any dates which are after a certain period (10 days from start date in you case).

jQuery datepicker allows this so does other datepickers.

EDIT: In your controller do something like this.

var newDate = new Date($scope.startdate.getFullYear(), $scope.startdate.getMonth(), $scope.startdate.getDate()+10);
$scope.dateOptions = {
 maxDate: newDate,
 dateFormat: 'dd/mm/YYYY'
};

And now you can pass dateOptions to your input.

Note: Post a minimal plunkr for faster resolution of your issues.