Angular.js - Update a model value through a function using a parameter

Question

Angular.js - Update a model value through a function using a parameter

I am currently faced with the following scenarios:

<input ng-model="something" />
<button ng-click="modify(something)">Modify</button>

Within the controller, there is this method:

$scope.modify = function (value) {
    value = value + " and some additional text";
};

Despite having the modify method in place, it seems to be ineffective.

My objective revolves around creating a function capable of altering an object from the model based on parameters provided. For instance, a function x that takes an object as input parameter, allowing modifications to said object within the function itself.

What steps should I take to accomplish this goal?

For further details, refer to this sample fiddle.

javascript angularjs

Answer 1

Answer №1

It's getting late, so I might be overlooking the obvious, but...

When passing a string, it is passed by value rather than reference. That's why I updated your ng-click to point to the object on the scope, instead of the actual value.

The modify function now references the scope instead of the variable itself.

Check out the code snippet below:

<div ng-app>
    <div ng-controller="SomeCtrl">
        <input ng-model="something" />
        <button ng-click="modify('something')">Modify</button>
    </div>
</div>

Here's the controller code:

function SomeCtrl($scope) {
    $scope.something = "test";

    $scope.modify = function (value) {
        $scope[value] = $scope[value] + " and this text";
    };
}

Answer 2

It's getting late, so I might be overlooking the obvious, but...

When passing a string, it is passed by value rather than reference. That's why I updated your ng-click to point to the object on the scope, instead of the actual value.

The modify function now references the scope instead of the variable itself.

Check out the code snippet below:

<div ng-app>
    <div ng-controller="SomeCtrl">
        <input ng-model="something" />
        <button ng-click="modify('something')">Modify</button>
    </div>
</div>

Here's the controller code:

function SomeCtrl($scope) {
    $scope.something = "test";

    $scope.modify = function (value) {
        $scope[value] = $scope[value] + " and this text";
    };
}

Answer 3

Answer №2

To improve your code, I recommend passing the variable name to the function and updating it as a key/value pair in the scope:

<button ng-click="update('example')">Update</button>

Next, modify your function like this:

$scope.update = function(value){
    $scope[value] = $scope[value] + " with this new text";
};

The issue lies in how Javascript handles variables - simple ones are passed by value, while objects and arrays are passed by reference. Consider using an object model with a 'text' key that gets updated by the function:

<button ng-click="update(data)">Update</button>

and update your function accordingly:

$scope.data = {text: "data"};
$scope.update = function(value){
    value.text = value.text + " with this new text";
};

Check out this JSFiddle link for the first approach.

Alternatively, you can also look at this second approach on JSFiddle.

Answer 4

To improve your code, I recommend passing the variable name to the function and updating it as a key/value pair in the scope:

<button ng-click="update('example')">Update</button>

Next, modify your function like this:

$scope.update = function(value){
    $scope[value] = $scope[value] + " with this new text";
};

The issue lies in how Javascript handles variables - simple ones are passed by value, while objects and arrays are passed by reference. Consider using an object model with a 'text' key that gets updated by the function:

<button ng-click="update(data)">Update</button>

and update your function accordingly:

$scope.data = {text: "data"};
$scope.update = function(value){
    value.text = value.text + " with this new text";
};

Check out this JSFiddle link for the first approach.

Alternatively, you can also look at this second approach on JSFiddle.

Answer 5

Answer №3

Manage the variables internally instead.

To simplify your function call, eliminate the variable:

<input ng-model="something" />
<button ng-click="update()">Update</button>

Within your controller, reference something as a $scope variable:

$scope.update = function () {
    $scope.something = $scope.something + " along with this extra text";
};

Answer 6

Manage the variables internally instead.

To simplify your function call, eliminate the variable:

<input ng-model="something" />
<button ng-click="update()">Update</button>

Within your controller, reference something as a $scope variable:

$scope.update = function () {
    $scope.something = $scope.something + " along with this extra text";
};

Answer 7

Answer №4

If you need assistance, you have the option to modify a model value through a function.

var app = angular.module('angularjs-starter', []);

app.controller('addRemoveVehicleCntrlr', function($scope) {

  $scope.vehicles = [{
    id: 'vehicle1'
  }];
  var allVins = [];
  $scope.addNewVehicle = function() {
    var newItemNo = $scope.vehicles.length + 1;
    $scope.vehicles.push({
      'id': 'vehicle' + newItemNo
    });
    // console.log($scope.vehicles);
  };
  $scope.getdetail = function(name, index, value) {
    console.log(name + index);
    allVins.splice(index, 1, {
      "vin": name,
      "trim": value
    });
    console.log(allVins);
    $scope.myval = "dd";
  }
  $scope.changeDetails = function(index, value) {
    // allVins.splice(index, 1, {"trim":value});
    allVins[index].trim = value
    console.log(allVins);
  }
  $scope.removeVehicle = function(index) {
    $scope.vehicles.splice(index, 1);
    allVins.splice(index, 1);
    console.log(allVins)
  };

});

<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.js"></script>
<div ng-app="angularjs-starter" ng-controller="addRemoveVehicleCntrlr">
  <div style="background:#cecece; padding:10px;">
    <div style="background:#EBEBEB; padding:10px; margin-bottom:3px" data-ng-repeat="vehicle in vehicles">
      <input type="text" ng-model="vehicle.name" name="" placeholder="Enter mobile number">
      <input type="button" value="Review" ng-click="getdetail(vehicle.name, $index, vehicle.value)" />
      <div id="myVal">{{myval}}</div>
      <a class="remove" ng-show="vehicles.length > 1" ng-click="removeVehicle($index)">Remove vehicle</a>
    </div>
  </div>
  <button class="addfields" ng-click="addNewVehicle()">Add Vehicle</button>
</div>

View on Plunker

Answer 8

If you need assistance, you have the option to modify a model value through a function.

var app = angular.module('angularjs-starter', []);

app.controller('addRemoveVehicleCntrlr', function($scope) {

  $scope.vehicles = [{
    id: 'vehicle1'
  }];
  var allVins = [];
  $scope.addNewVehicle = function() {
    var newItemNo = $scope.vehicles.length + 1;
    $scope.vehicles.push({
      'id': 'vehicle' + newItemNo
    });
    // console.log($scope.vehicles);
  };
  $scope.getdetail = function(name, index, value) {
    console.log(name + index);
    allVins.splice(index, 1, {
      "vin": name,
      "trim": value
    });
    console.log(allVins);
    $scope.myval = "dd";
  }
  $scope.changeDetails = function(index, value) {
    // allVins.splice(index, 1, {"trim":value});
    allVins[index].trim = value
    console.log(allVins);
  }
  $scope.removeVehicle = function(index) {
    $scope.vehicles.splice(index, 1);
    allVins.splice(index, 1);
    console.log(allVins)
  };

});

<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.js"></script>
<div ng-app="angularjs-starter" ng-controller="addRemoveVehicleCntrlr">
  <div style="background:#cecece; padding:10px;">
    <div style="background:#EBEBEB; padding:10px; margin-bottom:3px" data-ng-repeat="vehicle in vehicles">
      <input type="text" ng-model="vehicle.name" name="" placeholder="Enter mobile number">
      <input type="button" value="Review" ng-click="getdetail(vehicle.name, $index, vehicle.value)" />
      <div id="myVal">{{myval}}</div>
      <a class="remove" ng-show="vehicles.length > 1" ng-click="removeVehicle($index)">Remove vehicle</a>
    </div>
  </div>
  <button class="addfields" ng-click="addNewVehicle()">Add Vehicle</button>
</div>

View on Plunker

Angular.js - Update a model value through a function using a parameter

Answer №1

Answer №2

Answer №3

Answer №4

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