JSFiddle - React, Tailwind, and code Playground

HTML

<h1>ko 2.2.0</h1>
<p>click in the input field and press arrow down...</p> <p><strong>write occurs</strong></p>
<input data-bind="value: query, valueUpdate: 'afterkeydown'"/>
<div data-bind="text: query"></div>

<span>Subscribed non-computed</span>
<input data-bind="value: test, valueUpdate: 'afterkeydown'" />

JavaScript

var model=function(){
    var self=this;
    this.backingField = ko.observable("");
    this.query = ko.computed({read:function(){
        return self.backingField();
    },write:function(v){
        alert("write");
        self.backingField(v);
    }});
    this.test = ko.observable('');
    this.test.subscribe(function(newValue) {
        alert("The test value new name is " + newValue);
    });
}
    
var m=new model();

ko.applyBindings(m);