Personalizing a directive to prevent users from entering special characters in AngularJS

Question

Personalizing a directive to prevent users from entering special characters in AngularJS

I am currently diving deep into the world of AngularJS directives. My current project involves using a directive to prevent users from inputting special characters.

Below is the code snippet:

HTML

<input type="text" no-special-char ng-model="vm.customTag" class="form-control" value="" />

AngularJS Directive

app.directive('noSpecialChar', function () {
    return {
        require: 'ngModel',
        restrict: 'A',
        link: function (scope, element, attrs, modelCtrl) {
            modelCtrl.$parsers.push(function (inputValue) {
                if (inputValue == null)
                    return ''
                cleanInputValue = inputValue.replace(/[^\w\s]/gi, '');
                if (cleanInputValue != inputValue) {
                    modelCtrl.$setViewValue(cleanInputValue);
                    modelCtrl.$render();
                }
                return cleanInputValue;
            });
        }
    }
});

I have two requirements:

(1) I want to allow users to input a minus/dash '-' character, which is currently not permitted by my regex /[^\w\s]/gi. How can I modify it to allow the minus sign?

(2) The existing functionality only restricts special characters, but I also want to display a red alert message saying "special characters are not allowed" when a user attempts to input one. How can I achieve this additional feature?

Any guidance or assistance on these matters would be greatly appreciated!

Thank you

javascript angularjs regex angularjs-directive special-characters

Answer 1

Answer №1

Query #1

Your current regular expression is selecting every character that is not a word character or whitespace. If you want to include a hyphen, you need to add it to the list of characters not to be replaced.

Try using this updated regular expression:

/[^\w\s-]/gi

If there are any other characters you want to exclude from replacement, just append them after the hyphen.

See Live Demo on RegExr

Query #2

To track changes in your form content, listen for the keypress event and use .match() to detect special characters. This method will return a truthy string if special characters are found, otherwise false.

You can evaluate the result of .match() within an if statement and show an alert message when needed.

if (inputValue.match(/[^\w\s]/gi)) {
    // Display Alert Here!
}

Alternatively, you can implement the alert creation within the

if (cleanInputValue != inputValue)

condition. This approach achieves similar results as using .match(), detecting alterations made by .replace() and executing the code inside the if block accordingly.

Answer 2

Query #1

Your current regular expression is selecting every character that is not a word character or whitespace. If you want to include a hyphen, you need to add it to the list of characters not to be replaced.

Try using this updated regular expression:

/[^\w\s-]/gi

If there are any other characters you want to exclude from replacement, just append them after the hyphen.

See Live Demo on RegExr

Query #2

To track changes in your form content, listen for the keypress event and use .match() to detect special characters. This method will return a truthy string if special characters are found, otherwise false.

You can evaluate the result of .match() within an if statement and show an alert message when needed.

if (inputValue.match(/[^\w\s]/gi)) {
    // Display Alert Here!
}

Alternatively, you can implement the alert creation within the

if (cleanInputValue != inputValue)

condition. This approach achieves similar results as using .match(), detecting alterations made by .replace() and executing the code inside the if block accordingly.

Answer 3

Answer №2

Following feedback and comments:

This solution provides the functionality you requested, albeit in a non-conventional "Angular" way - it still accomplishes the desired outcome.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" ng-app="ns.test">
<head>
    <title>Test</title>
    <!-- http://stackoverflow.com/questions/36303590/customizing-directive-to-restrict-the-user-to-input-special-characters-angular -->

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angular.min.js"></script>

    <style>
        .input {
            padding: 20px;
            margin: 50px;
        }

            .input input {
                border: solid 1px black;
                font-family: Tahoma;
                font-size: larger;
                padding: 5px;
            }

        .err {
            color: red;
            padding: 5px;
            margin: 10px;
            font-family: Tahoma;
            font-size: larger;
            display:inline;
        }
    </style>

    <script type="text/javascript">

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

        app.controller('testController', function ($scope) {
            $scope.item = 'item1';
            $scope.item2 = 'item2';
            $scope.item3 = 'item3';
            $('input:first').focus();
        });

        var noSpecialChar = function () {
            return {
                restrict: 'A',
                require: '?ngModel',
                link: function (scope, elm, attr, modelCtrl) {
                    if (!modelCtrl) return;

                    modelCtrl.$parsers.push(function (inputValue) {
                        if (inputValue == null)
                            return ''

                        var parent = $(elm).parent();

                        cleanInputValue = inputValue.replace(/[^a-z0-9-_]+/gi, '');
                        if (cleanInputValue != inputValue) {
                            if (parent.find(".err").length == 0)
                                parent.append("<div class=\"err\">Invalid Characters</div>"); // change the class here to your bootstrap alert classes
                        } else
                            parent.find(".err").remove();

                        return cleanInputValue;
                    });
                }
            };
        };

        app.directive('noSpecialChar', noSpecialChar);

    </script>
</head>
<body data-ng-controller="testController">
    <form name="userForm" novalidate>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item" />
        </div>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item2" />
        </div>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item3" />
        </div>
    </form>
</body>
</html>

Answer 4

Following feedback and comments:

This solution provides the functionality you requested, albeit in a non-conventional "Angular" way - it still accomplishes the desired outcome.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" ng-app="ns.test">
<head>
    <title>Test</title>
    <!-- http://stackoverflow.com/questions/36303590/customizing-directive-to-restrict-the-user-to-input-special-characters-angular -->

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angular.min.js"></script>

    <style>
        .input {
            padding: 20px;
            margin: 50px;
        }

            .input input {
                border: solid 1px black;
                font-family: Tahoma;
                font-size: larger;
                padding: 5px;
            }

        .err {
            color: red;
            padding: 5px;
            margin: 10px;
            font-family: Tahoma;
            font-size: larger;
            display:inline;
        }
    </style>

    <script type="text/javascript">

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

        app.controller('testController', function ($scope) {
            $scope.item = 'item1';
            $scope.item2 = 'item2';
            $scope.item3 = 'item3';
            $('input:first').focus();
        });

        var noSpecialChar = function () {
            return {
                restrict: 'A',
                require: '?ngModel',
                link: function (scope, elm, attr, modelCtrl) {
                    if (!modelCtrl) return;

                    modelCtrl.$parsers.push(function (inputValue) {
                        if (inputValue == null)
                            return ''

                        var parent = $(elm).parent();

                        cleanInputValue = inputValue.replace(/[^a-z0-9-_]+/gi, '');
                        if (cleanInputValue != inputValue) {
                            if (parent.find(".err").length == 0)
                                parent.append("<div class=\"err\">Invalid Characters</div>"); // change the class here to your bootstrap alert classes
                        } else
                            parent.find(".err").remove();

                        return cleanInputValue;
                    });
                }
            };
        };

        app.directive('noSpecialChar', noSpecialChar);

    </script>
</head>
<body data-ng-controller="testController">
    <form name="userForm" novalidate>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item" />
        </div>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item2" />
        </div>
        <div class="input">
            <input type="text" data-no-special-char data-ng-model="item3" />
        </div>
    </form>
</body>
</html>

Personalizing a directive to prevent users from entering special characters in AngularJS

Answer №1

Answer №2

Similar questions

What could be causing the Toast message to not show up in react-native-root-toast?

Unable to retrieve the variable within the event handler

Issues with JavaScript Array Splice Function

How to position items at specific coordinates in a dropdown using JavaScript

Error: $this.text is throwing a TypeError and is not working as a function

What is the root cause behind the recurring appearance of this line in Angular/D3.js?

What is the process for utilizing "yarn create <pkg-name>" command?

Submit image on Laravel platform from canvas

Validator returns undefined when expressing invalid data

The filtering feature of ng-grid doesn't seem to function properly in Internet Explorer 8 when using blank

Prestashop: Eliminate user uploaded files with AJAX for seamless experience

Incorporate live Twitch streaming onto a web platform

Issue encountered while attempting to utilize the concat method to condense an array

Unable to access the attributes of the mongoose model

The Vue property or method is unrecognized when utilizing the non-minified version

Trouble with transmitting jQuery form information to PHP page

Despite the presence of data within the array, the React array returns empty when examined using the inspect element tool

Remove leading and trailing spaces from all items in the list

What causes variables and functions to behave differently when it comes to hoisting?

Navigating attributes originating from the key in JSON: A guide to effective management