JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="prova" name="prova" value="saluti" />
<input type="button" onclick="fromStringToHex(document.getElementById('prova').value);" value="prova">

JavaScript

fromStringToHex = function(string)
{
    var hex, i;
    var result = "";
    for (i=0; i<string.length; i++) {
        alert('decimale'+string.charCodeAt(i).toString(10));
        alert('esadecimale'+string.charCodeAt(i).toString(16));
        hex = string.charCodeAt(i).toString(16);
        result += ("0"+hex).slice(-2);
    }
    return result;
}