Custom filters

Simple filter example

Filters format the value of an expression for display to the user. They can be used in view templates, controllers or services. This example creates a filter (addZ) then uses it in a view. All this filter does is add a capital ‘Z’ to the end of the string.

example.js

angular.module('main', [])
    .filter('addZ', function() {
            return function(value) {
                return value + "Z";
            }
     })
    .controller('MyController', ['$scope', function($scope) {
        $scope.sample = "hello";
    }])

example.html

Inside the view, the filter is applied with the following syntax: { variable | filter}. In this case, the variable we defined in the controller, sample, is being filtered by the filter we created, addZ.

<div ng-controller="MyController">
   <span>{{sample | addZ}}</span>
</div>

Expected output

helloZ

Use a filter in a controller, a service or a filter

You will have to inject $filter:

angular
  .module('filters', [])
  .filter('percentage', function($filter) {
    return function (input) {
      return $filter('number')(input * 100) + ' %';
    };
  });

Create a filter with parameters

By default, a filter has a single parameter: the variable it is applied on. But you can pass more parameter to the function:

angular
  .module('app', [])
  .controller('MyController', function($scope) {
    $scope.example = 0.098152;
  })
  .filter('percentage', function($filter) {
    return function (input, decimals) {
      return $filter('number')(input * 100, decimals) + ' %';
    };
  });

Now, you can give a precision to the percentage filter:

<span ng-controller="MyController">{{ example | percentage: 2 }}</span>
=> "9.81 %"

… but other parameters are optional, you can still use the default filter:

<span ng-controller="MyController">{{ example | percentage }}</span>
=> "9.8152 %"