如果没有结果或有 null 值，如何清除输入的值？

Question

I am trying to clear the value of an input depending if it finds or not an id, if it finds an existing id, js updates the value of an input, but if it doesn't it keeps the last one found but I need to have the value clear, can someone tell me what is wrong:

function driverdata(valueid)
{
    var numero_id = valueid;
    //console.log(valueid)
    var idselect = document.getElementById('driver'+id_number).value;
    document.getElementById("idinsearch"+ id_number).value = idselect;
    //console.log(idselect);
    var placa = document.getElementById("searchable"+idselect).value;
    console.log(placa);
    if (placa != null) {
        document.getElementById("placa"+ id_number).value = placa;
    } else {
        document.getElementById("placa"+ id_number).value = "";
    }
}

Answer 1

In the method driverdata you don't define variable id_number so it's undefined when you try get element by id

So if id_number is equal to the parameter of the method you can directly use it

moreover to clear value you are right it's elem.value = ""

withour yout html i can propose you the following one => your script run

 function driverdata(numberId) { var idselect = document.getElementById('driver'+numberId).value; document.getElementById("idinsearch"+ numberId).value = idselect; var placa = document.getElementById("searchable"+idselect).value; if (placa.= null) { document.getElementById("placa"+ numberId);value = placa. } else { document.getElementById("placa"+ numberId);value = ""; } }

 <div onclick="driverdata(1)"> click me<br/> driver<input id="driver1" value="1"/><br/> idinsearch<input id="idinsearch1"/><br/> <div id="searchable1"> input that will be clear <input id="placa1" value="test"/> </div> </div>