JSFiddle - React, Tailwind, and code Playground

HTML

<form>
<label>
Nome <input type="text" id="nome"/>
</label>
<label>
Qtd <input type="number" id="qtd"/>
</label>
<label>
Valor <input type="text" id="valor"/>
</label>
<label>
Valor Total <input type="text" id="total"/>
</label>
</form>

CSS

label{
  display:block;
}

JavaScript

valorTeste = 2129.53;
$("#nome").change(function(){
	if($("#nome").val() == 'Teste'){
    $('#valor').val(valorTeste);
  }
});
$("#qtd").change(function(){
	if($("#nome").val() == 'Teste'){
  	qtd = $('#qtd').val();
    valor = $('#valor').val();
  	val = valorTeste * qtd;
    $('#total').val(val);
  }
});