How to recalculate data on a page in Angular?

Question

JavaScript

The user enters data into inputs.
In other inputs, you need to perform actions on the data and output, how to do it so that every time the data changes, a recalculation and output occurs? How to hang a handler on a form?
It doesn't work like that

<input value="{{Math.round(wh.price*wh.count/100)}}">

Answer 1

do it in the controller, not in the views, and in the views only ng-model and no formulas in the views.
example (the same method was suggested by @kirill-93)
Profit - you can conveniently and beautifully cover this matter with tests, everything is predictable, it is convenient to write, and the performance of such a solution is much better. Well, yes, as formulas become more complex, element dependencies, etc. it's much easier to sort it out.

Answer 2

DEMO .

angular.module('toster', [])

.controller('MainCtrl', function($scope) {
    $scope.data = {
        price: 0,
        count: 0
    };
    
    $scope.$watchCollection('data', function(data) {
        var computed = 0;
        
        var count = parseInt(data.count, 10);
        
        if (count) {
            computed = Math.round(data.price * count / 100);
        }
        
        $scope.computed = computed;
    });
});

Answer 3

<input ng-model="superModel">

scope.$watch("Math.round(wh.price*wh.count/100)", function(val){
    scope.superModel = val;
})