JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" placeholder="Enter some text..." data-bind="value: text, valueUpdate: 'afterkeydown'" />
<select data-bind="options: suggestions"></select>
<button ></button>

JavaScript

var VM = function () {
    
    this.text = ko.observable('').extend({ required: true })

    this.suggestionStrings = [
        'Hello',
        'world',
        'name',
        'richard'
    ];

    this.suggestions = ko.computed(function () {

        var text = this.text();

        return ko.utils.arrayFilter(this.suggestionStrings, function (str) {
            return new RegExp(text, 'i').test(str);
        });
    }, this);
};

ko.applyBindings(new VM());