Is there masked input plugin for knockout.js using extenders?

Question

I\'ve seen this post - it shows one possible solution. But I would like to have a more elegant way of doing masked input.

It should also play nicely with knockout valida

Answer 1

Just take the code from the answer in that link and put it in a extender (Written on free hand, can have errors)

ko.extenders.masked = function(observable, options) {
    return ko.computed({
        read: function() {
            return '$' + this.observable().toFixed(2);
        },
        write: function(value) {
            // Strip out unwanted characters, parse as float, then write the raw data back to the underlying observable
            value = parseFloat(value.replace( /[^\.\d]/g , ""));
            observable(isNaN(value) ? 0 : value); // Write to underlying storage
        }
    });
};

edit: You probably want to supply the mask as a options instead of having it hardcoded to USD etc

update: If you want to use the mask plugin from riceboyler's answer but with extenders you can do

ko.extenders.mask = function(observable, mask) {
    observable.mask = mask;
    return observable;
}


var orgValueInit = ko.bindingHandlers.value.init;
ko.bindingHandlers.value.init = function(element, valueAccessor) {
    var mask = valueAccessor().mask;
    if(mask) {
        $(element).mask(mask);
    }

    orgValueInit.apply(this, arguments);
}

http://jsfiddle.net/rTK6G/

Answer 2

I tried to use the first answer but it did not work with ko.validation plug in. My validation errors were not being displayed.

I wanted to have little bit more intuitive ko binder. Here is my solution. I am using jquery.inputmask plug in. I also wipe out the property on my viewmodel if not value entered.

    ko.bindingHandlers.mask = {
        init: function (element, valueAccessor, allBindingsAccessor, viewModel,     bindingContext) {
            var mask = valueAccessor() || {};
            $(element).inputmask({ "mask": mask, 'autoUnmask': false });
            ko.utils.registerEventHandler(element, 'focusout', function () {
                var value = $(element).inputmask('unmaskedvalue');            
                if (!value) {
                    viewModel[$(element).attr("id")]("");                
                }
            });
        }
    };

Here is the usage:

<input type="text" data-bind="value: FEIN, mask: '99-9999999'" id="FEIN" >

Answer 3

You can use this homemade solution, work perfectly for me:

My Binding knockout call masked inspired from the net, i added some managed language and update from different event. Also I use this js library for using basically : https://plugins.jquery.com/maskedinput/

You can see in my binding the term "allBindingsAccessor().mask" this is from the library maskedinput

 ko.bindingHandlers.masked = {
    init: function (element, valueAccessor, allBindingsAccessor) {
        var mask = allBindingsAccessor().mask || {},
        getCaretPosition,
        setCaretPosition;

        // Permet d'obtenir la position du curseur
        getCaretPosition = function getCaretPosition(element) {
            // Initialise la position
            var caretPos = 0, sel;

            // IE 
            if (document.selection) {
                // Donne le focus à l'élément
                element.focus();
                // Afin d'obtenir la position du curseur
                sel = document.selection.createRange();
                // On place le curseur à 0
                sel.moveStart('character', -element.value.length);
                caretPos = sel.text.length;
            }
                // Firefox 
            else if (element.selectionStart || element.selectionStart === '0') {
                caretPos = element.selectionStart;
            }
            return (caretPos);
        };

        // Permet de définir la position du curseur en fonction d'une position donnée
        setCaretPosition = function setCaretPosition(element, pos) {
            var range;
            if (element.setSelectionRange) {
                element.focus();
                element.setSelectionRange(pos, pos);
            }
            else if (element.createTextRange) {
                range = element.createTextRange();
                range.collapse(true);
                range.moveEnd('character', pos);
                range.moveStart('character', pos);
                range.select();
            }
        };

        // Définition du masque inséré dans le champ
        if (configSvc.culture === "fr-FR") {
            // Cas francais
            $(element).mask("99/99/9999", { placeholder: "JJ/MM/AAAA" });
        }
        else {
            // Cas anglophone
            $(element).mask("99/99/9999", { placeholder: "MM/DD/YYYY" });
        }

        // On capte l'événement d'appuie sur une touche 
        ko.utils.registerEventHandler(element, 'keypress', function () {
            var observable = valueAccessor(),
                position;
            // Afin de résoudre le pb de déplacement du curseur a la fin du mask lors de la mise à jour de l'observable knockout
            if ($(element).val().length === 10) {
                // On récupère la dernière position
                position = getCaretPosition(this);
                // On met à jour la valeur de l'obersable (en cas de sauvegarde) 
                observable($(element).val());
                // On force la position du curseur apres mise à jour de l'observable à la derniere position récupéré
                setCaretPosition(this, position);
            }
        });

        // On capte l'événement de perte de focus pour mettre l'obersable à jour
        ko.utils.registerEventHandler(element, 'blur', function () {
            var observable = valueAccessor();
            observable($(element).val());
        });

        // On capte l'événement change pour mettre l'obersable à jour
        ko.utils.registerEventHandler(element, 'change', function () {
            var observable = valueAccessor();
            observable($(element).val());
        });
    },
    update: function (element, valueAccessor) {
        var value = ko.utils.unwrapObservable(valueAccessor());
        $(element).val(value);
    }

};

in my html page, i use this observable "masked" :

<input type="text" id="head-birthDate" class="form-control" data-bind="masked: birthDate" />

Finally in my js :

birthDate is just an observable

this.birthDate = ko.observable();

Answer 4

If you wanted to use the excellent Masked Input Plugin in Knockout, it's pretty easy to write a basic custom binding rather than an extender.

ko.bindingHandlers.masked = {
    init: function(element, valueAccessor, allBindingsAccessor) {
        var mask = allBindingsAccessor().mask || {};
        $(element).mask(mask);
        ko.utils.registerEventHandler(element, 'focusout', function() {
            var observable = valueAccessor();
            observable($(element).val());
        });
    }, 
    update: function (element, valueAccessor) {
        var value = ko.utils.unwrapObservable(valueAccessor());
        $(element).val(value);
    }
};

And then in your HTML:

<input type="text" data-bind="masked: dateValue, mask: '99/99/9999'" />
<input type="text" data-bind="masked: ssnValue, mask: '999-99-9999'" />

And so on with various masks. This way, you can just put the mask right in your databinding, and it allows a ton of flexibility.

Answer 5

Well done, riceboyler. I took your code and extended it a little in order to use the "placeholder" property of the Masked Input Plugin:

    ko.bindingHandlers.masked = {
        init: function (element, valueAccessor, allBindingsAccessor) {
            var mask = allBindingsAccessor().mask || {};
            var placeholder = allBindingsAccessor().placeholder;
            if (placeholder) {
                $(element).mask(mask, { placeholder: placeholder });
            } else {
                $(element).mask(mask);
            }
            ko.utils.registerEventHandler(element, "blur", function () {
                var observable = valueAccessor();
                observable($(element).val());
            });
        },
        update: function (element, valueAccessor) {
            var value = ko.utils.unwrapObservable(valueAccessor());
            $(element).val(value);
        }
    };

HTML with placeholder:

    <input id="DOB" type="text" size="12" maxlength="8" data-bind="masked: BirthDate, mask: '99/99/9999', placeholder: 'mm/dd/yyyy', valueUpdate: 'input'"/>

HTML without placeholder:

    <input id="DOB" type="text" size="12" maxlength="8" data-bind="masked: BirthDate, mask: '99/99/9999', valueUpdate: 'input'"/>

The KO binding works either way.