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

Knockout has extenders for this. Check This from knockoutjs.com explaining how to use observable extenders to force input to be numeric. I paste the code from the documentation here:

Source code: View

 (round to whole number)
 (round to two decimals)

Source code: View model

ko.extenders.numeric = function(target, precision) {
    //create a writable computed observable to intercept writes to our observable
    var result = ko.pureComputed({
        read: target,  //always return the original observables value
        write: function(newValue) {
            var current = target(),
                roundingMultiplier = Math.pow(10, precision),
                newValueAsNum = isNaN(newValue) ? 0 : parseFloat(+newValue),
                valueToWrite = Math.round(newValueAsNum * roundingMultiplier) / roundingMultiplier;

            //only write if it changed
            if (valueToWrite !== current) {
                target(valueToWrite);
            } else {
                //if the rounded value is the same, but a different value was written, force a notification for the current field
                if (newValue !== current) {
                    target.notifySubscribers(valueToWrite);
                }
            }
        }
    }).extend({ notify: 'always' });

    //initialize with current value to make sure it is rounded appropriately
    result(target());

    //return the new computed observable
    return result;
};

function AppViewModel(one, two) {
    this.myNumberOne = ko.observable(one).extend({ numeric: 0 });
    this.myNumberTwo = ko.observable(two).extend({ numeric: 2 });
}

ko.applyBindings(new AppViewModel(221.2234, 123.4525));