make an input only-numeric type on knockout

Question

i read many tutorials but i dont know how to do this, this is the input

input(type=\"text\",name=\"price\",id=\"price\"data-bind=\"text: price,valueUpdate:[\         


        

Answer 1

I had a similar problem.

I also needed to ensure inter values only, and for IE9 and up (so type=numberical was not enough), and since we have a lot of international customers, i could not rely on keycodes either, so the following is what i ended up with:

//In my js class method (self is this as usual)
self.ensureNumberical = function (data, e) {
    var keyValue = e.key;
    if (keyValue.match(/[0-9]/g)) {
        return true;
    }
    return false;
}

//In my MVC View
data-bind="event: { keypress: ensureNumberical }"

Answer 2

Best for today's scenerio https://github.com/Knockout-Contrib/Knockout-Validation

run the snippet below. entering a non digit or something more than 255 will cause the message to display.

function model() {
  var self = this;
  this.myObj = ko.observable().extend({ digit: true }).extend({ max: 255});
  }
  
  var mymodel = new model();

$(document).ready(function() {
  ko.validation.init();
  ko.applyBindings(mymodel);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout-validation/2.0.3/knockout.validation.min.js"></script>

enter a digit less than or equal to  255 <input type="text" data-bind="textInput: myObj">

<p>
  Enter something other than a digit or over 255 will cause an error.
</p>

courtesy: Bryan Dellinger: https://stackoverflow.com/a/42940109/3868653

Answer 3

I know this question is a year old but let me post this for the sake of feature visitor of the page.

Check this out:

ko.bindingHandlers.numericnumbers = {
init: function (element) {
    $(element).on('keypress', function (number) {
        number = (number) ? number : window.event;
        var charcode = (number.which) ? number.which : number.keyCode;
        if (charcode > 31 && (charcode < 48 || charcode > 75))
            number.preventDefault();
    });
}};

Answer 4

Is better to create custom binding http://knockoutjs.com/documentation/custom-bindings.html which accept only allowed characters [0-9,.] as numeric representation.

put this line into your view

<input id="text" type="text" data-bind="numeric, value: number">

put this line into your model (remember to bind number as observable property)

ko.bindingHandlers.numeric = {
    init: function (element, valueAccessor) {
        $(element).on("keydown", function (event) {
            // Allow: backspace, delete, tab, escape, and enter
            if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
                // Allow: Ctrl+A
                (event.keyCode == 65 && event.ctrlKey === true) ||
                // Allow: . ,
                (event.keyCode == 188 || event.keyCode == 190 || event.keyCode == 110) ||
                // Allow: home, end, left, right
                (event.keyCode >= 35 && event.keyCode <= 39)) {
                // let it happen, don't do anything
                return;
            }
            else {
                // Ensure that it is a number and stop the keypress
                if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode > 105)) {
                    event.preventDefault();
                }
            }
        });
    }
};

Answer 5

Create you data-bind pointing at your shiny new code:

<input id="price" name="price" type="text" data-bind="numeric">

Shiny new knockout code:

price = ko.observable();
price.subscribe(function(newValue) {
    price = newValue.replace(/[\D\.]/g, '');
});

This means that every time you update the price, it will apply the logic in the function (in this case stripping out anything that isn't a number or a period), and apply it directly to the price. You can also add other validation or cool features here, like adding a currency sybmol at the start, keeping it to 2 decimal places, etc...

Answer 6

With the help of "keydown" event we can restrict other key's in text box which should hold numeric values.

$(document).ready(function(){                
        $("selector").on("keydown", function (e) {
            //numbers, delete, backspace, arrows
            var validKeyCodes = [8, 9, 37, 38, 39, 40, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57];
            if (!($.inArray(e.keyCode, validKeyCodes) >= 0))
                    e.preventDefault();                 
        });           
    });