JSFiddle - React, Tailwind, and code Playground

HTML

<form name="data">
        <input name="asd1" title="text1" id="asd1"><br>
        <input name="asd2" title="text2" id="asd2"><br>
        <input type="button" name="but1" value="update">
    
        <textarea rows=6 cols=80 name="conclus" id="idConclus"></textarea>
    </form>

JavaScript

var inputs = ['asd1', 'asd2'];
var form = document.data;
var button = form.but1;
var textarea = form.conclus;
button.addEventListener('click', function() {
    var text = Array();
    for(var i = 0, length = inputs.length; i < length; i++) {
        var input = form[inputs[i]];
        text.push(input.title + " - " + input.value);
    }
    textarea.value = text.join(' ');
}, false);