AngularJS - cascade binding on textboxes

Question

I want to do cascade operations in textboxes with Angular. Assume I have 4 numbers in existing textboxes, I want to:

Sum first two numbers in first textbox
Sum next two numbers in second textbox
Sum both results in third textbox

This is HTML example of what I want to do. I know it's not working, but I'm searching for most elegant solution of my problem.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>AngularTest</title>
</head>
<body ng-app>
    <form>
        <fieldset>
            <label for="first">Tag100</label>
            <input type="number" id="first" min="0" ng-model="tag100" placeholder="0" /><br/>
            <label for="second">Tag200</label>
            <input type="number" id="second" min="0" ng-model="tag200" placeholder="0" /><br/>
            <label for="third">Tag300</label>
            <input type="number" id="third" min="0" ng-model="tag300" placeholder="0" /><br/>
            <label for="fourth">Tag400</label>
            <input type="number" id="fourth" min="0" ng-model="tag400" placeholder="0" /><br/>
            <label for="onetwo">Tag 500 = Tag100 + Tag200</label>
            <input type="number" id="onetwo" min="0" ng-model="tag500" placeholder="0" value="{{tag100+tag200}}"/><br/>
            <label for="threefour">Tag 600 = Tag300 + Tag400</label>
            <input type="number" id="threefour" min="0" ng-model="tag600" placeholder="0" value="{{tag300+tag400}}"/><br/>
            <label for="fivesix">Tag 700 = Tag500 + Tag600</label>
            <input type="number" id="fivesix" min="0" ng-model="tag700" placeholder="0" value="{{tag500+tag600}}" /><br/>
        </fieldset>
    </form>

    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
</body>
</html>

Vinay K · Accepted Answer · 2015-02-25 16:57:00Z

1

will not work when ng-model is provided.

Here is the solution:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>AngularTest</title>
</head>
<body ng-app="myApp">
    <form data-ng-controller="AppCtrl">
        <fieldset>
            <label for="first">Tag100</label>
            <input type="number" id="first" min="0" ng-model="tag100" placeholder="0" /><br/>
            <label for="second">Tag200</label>
            <input type="number" id="second" min="0" ng-model="tag200" placeholder="0" /><br/>
            <label for="third">Tag300</label>
            <input type="number" id="third" min="0" ng-model="tag300" placeholder="0" /><br/>
            <label for="fourth">Tag400</label>
            <input type="number" id="fourth" min="0" ng-model="tag400" placeholder="0" /><br/>
            <label for="onetwo">Tag 500 = Tag100 + Tag200</label>
            <input type="number" id="onetwo" min="0" ng-model="tag500" placeholder="0" /><br/>
            <label for="threefour">Tag 600 = Tag300 + Tag400</label>
            <input type="number" id="threefour" min="0" ng-model="tag600" placeholder="0" /><br/>
            <label for="fivesix">Tag 700 = Tag500 + Tag600</label>
            <input type="number" id="fivesix" min="0" ng-model="tag700" placeholder="0" /><br/>
        </fieldset>
    </form>

    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<script>

    angular.module('myApp', [])
    .controller('AppCtrl', function ($scope) {
        $scope.$watch(function () {
            $scope.tag500 = ($scope.tag100 || 0) + ($scope.tag200 || 0);
            $scope.tag600 = ($scope.tag300 || 0) + ($scope.tag400 || 0);
            $scope.tag700 = ($scope.tag500 || 0) + ($scope.tag600 || 0);
        })
    });

</script>
</body>
</html>

answered Feb 25, 2015 at 16:57

Vinay K

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2 Comments

Marko Tošić Over a year ago

Thank you for the working solution. I need to have hundreds/thousand of those fields (really large form). Will scope.watch affect performance?

Vinay K Over a year ago

Yes.. Definitely. for each and every key-up that function will be triggered. Read about ng-model-options at docs.angularjs.org/api/ng/directive/ngModelOptions

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