How to disable an input field using Javascript?
问题 I'm starting with Javascript, I wrote this function: function disableField() { if( document.getElementById("valorFinal").length > 0 ) ) { document.getElementById("cantidadCopias").disabled = true; } } Which disables the second field named cantidadCopias if the first one is filled. <label> <span>Valor final:</span> <input type="text" class="input_text" name="valorFinal" id="valorFinal" onkeydown="disableField()"/> </label> <label> <span>Cantidad de Copias:</span> <input type="text" class=