Modifying a data point using various inputs in AngularJS

Question

Modifying a data point using various inputs in AngularJS

In this scenario, my goal is to create a system where a remaining amount decreases as the user inputs values into a series of text fields.

Using an angular loop to generate these text fields, I need to update the "remainingAmount" variable accordingly. For instance, if the initial remaining amount is 40 and the user enters 10 into the first field, the remaining amount should decrease to 30, continuing until it reaches 0.


    <div class="row">
            <div class="col text-center error">
                <span ng-model="remainingAmount">{{ remainingAmount }}</span> left to distribute
            </div>
        </div>
    </div>

    <div class="list">

        <div class="item item-button-right" ng-repeat="user in users">
            {{ user.first_name }} {{ user.last_name }}
            <span class="item-note">
                <input type="text"  />
            </span>
        </div>

    </div>

Plunk: http://plnkr.co/edit/NmwTfGNC7jJyRL1kADCJ

javascript angularjs angularjs-ng-repeat angular-ngmodel

Answer 1

Answer №1

To efficiently manage your inputs, consider binding them to your model. This way, you can easily calculate the remaining amount whenever there is a change in one of the inputs:

HTML:

<input type="text" ng-model="user.amount" ng-change="calc()" />

JS:

$scope.calc = function() {
  var total = 0, user;
  for (user in $scope.users) {
    total += parseInt($scope.users[user].amount, 10) || 0;
  }
  $scope.remainingAmount = Math.max($scope.startAmount - total, 0);
}

Take a look at the example on Plunker

Answer 2

To efficiently manage your inputs, consider binding them to your model. This way, you can easily calculate the remaining amount whenever there is a change in one of the inputs:

HTML:

<input type="text" ng-model="user.amount" ng-change="calc()" />

JS:

$scope.calc = function() {
  var total = 0, user;
  for (user in $scope.users) {
    total += parseInt($scope.users[user].amount, 10) || 0;
  }
  $scope.remainingAmount = Math.max($scope.startAmount - total, 0);
}

Take a look at the example on Plunker

Answer 3

Answer №2

Here is a straightforward example with no validation or additional features. I noticed that an object was being used as an array, so I made a switch to using an actual array. Additionally, I changed the input from text to number in order to prevent the need for re-parsing the number since Angular automatically sets the property as a string:

Link to plunker demo

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
    var maxAmount = 40;
    $scope.remainingAmount = maxAmount;
    $scope.users = [
        {'id':1, 'first_name':'Joe', 'last_name': 'Bloggs', amountUsed: 0},
        {'id':2, 'first_name':'Chris', 'last_name': 'Scott', amountUsed: 0}
    ];

    $scope.updateUsage = function(){
      var totalUsed = 0;

      for (var i = 0; i < $scope.users.length; i++) {
        var u = $scope.users[i];
        totalUsed += u.amountUsed;
      }

      $scope.remainingAmount = maxAmount - totalUsed;
    }
});

Answer 4

Here is a straightforward example with no validation or additional features. I noticed that an object was being used as an array, so I made a switch to using an actual array. Additionally, I changed the input from text to number in order to prevent the need for re-parsing the number since Angular automatically sets the property as a string:

Link to plunker demo

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
    var maxAmount = 40;
    $scope.remainingAmount = maxAmount;
    $scope.users = [
        {'id':1, 'first_name':'Joe', 'last_name': 'Bloggs', amountUsed: 0},
        {'id':2, 'first_name':'Chris', 'last_name': 'Scott', amountUsed: 0}
    ];

    $scope.updateUsage = function(){
      var totalUsed = 0;

      for (var i = 0; i < $scope.users.length; i++) {
        var u = $scope.users[i];
        totalUsed += u.amountUsed;
      }

      $scope.remainingAmount = maxAmount - totalUsed;
    }
});

Modifying a data point using various inputs in AngularJS

Answer №1

Answer №2

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