JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="inputBox">
<div id="autoComplete"></div>

JavaScript

var suggestions = ["bank", "back", "peter", "hindu", "hindu2"],
    input = document.getElementById('inputBox'),
    resultBox = document.getElementById('autoComplete');

input.oninput = function(){
    resultBox.innerHTML = '';
    var inputVal = input.value;
    if(inputVal.length > 2){
        for(var i = 0; i < suggestions.length; i++){
            if (suggestions[i].indexOf(inputVal) === 0) {
                resultBox.innerHTML =
                resultBox.innerHTML + ' ' + suggestions[i];
            }
        }
    }
}