Introdution example from KnockoutJs

//HTML
<p>First name: <strong data-bind="text: firstName"></strong></p>
<p>Last name: <strong data-bind="text: lastName"></strong></p>

<p>First name: <input data-bind="value: firstName" /></p>
<p>Last name: <input data-bind="value: lastName" /></p>

<p>Full name: <strong data-bind="text: fullName"></strong></p>

<button data-bind="click: capitalizeLastName">Go caps</button>

----------------------------------------------------------------------

//JS
function AppViewModel() {
    this.firstName = ko.observable("Bert");
    this.lastName = ko.observable("Bertington");
    
    this.fullName = ko.computed(function() {
    return this.firstName() + " " + this.lastName();    
    }, this);
    
    this.capitalizeLastName = function() {
        var currentVal = this.lastName();        // Read the current value
        this.lastName(currentVal.toUpperCase()); // Write back a modified value
    };
}

ko.applyBindings(new AppViewModel());



Download KnockOutJS