Fundamentals of Filtering with Angular

Greetings everyone, I am new to Angular and seeking assistance. I am encountering difficulties with Angular filters when using a data-binded value.

<!DOCTYPE html>
<html>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
    <body>
        <div ng-app="myApp" ng-controller="myCtrl">

            Enter a value for conversion to hexadecimal: <input type="text" ng-model="whatever">

            <h1>{{ whatever }}</h1>

        </div>

        <p>I have created a custom service with a method that converts a number into its hexadecimal equivalent.</p>

        <script>
            var app = angular.module('myApp', []);

            app.service('hexafy', function(x) {
                this.myFunc = function (x) {
                    return x.toString(16);
                }
            });
            app.controller('myCtrl', function($scope) {

            });
            app.filter('myFormat',['hexafy', function(hexafy) {
                return function(x) {
                    return hexafy.myFunc(x);
                };
            }]);
        </script>

    </body>
</html>

I am facing an issue with the following line of code :

<h1>{{ foo | myFormat }}</h1>

Why is it not functioning as expected?

The following line works fine :

<h1>{{ 255 | myFormat }}</h1>

This also functions correctly :

<h1>{{ foo }}</h1>

How can I resolve the combination of the two not working together? Any help is appreciated. Thank you.

Answer №1

Dealing with the absence of a value in a custom filter. The variable foo is currently undefined, and you are attempting to call toString on it within the hexafy service.

Code Update for the Filter

app.filter('myFormat',['hexafy', function(hexafy) {
                return function(x) {
                    if(!x){
                       return x;
                     }
                    return hexafy.myFunc(x);
                };
            }]);

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