How to display alert after Eval() error?

Question

I have a calculator that works more or less like this:

[bolas][+][preco da bola]

I see the string replacing [XXXXXXX] with the corresponding value and use Eval to perform the calculation. But there may be cases of error when for example the calculation gets like this:

eval("5 + [preco da bola]");

• The JS code stops when this error occurs?
• If the code stops I have a way to prevent it from running?
• I can detect the error and send a custom Alert?

Answer 1

Would that be?....

try{
    eval("5 + [preco da bola]");
}catch(e){
    console.log(e);
}

Answer 2

You can always make a mistake by not crossing over to the client’s side with:

try{
    // o código que pode dar erro aqui
}
catch(erro){
    // este codigo é corrido quando houver erros. A variável "erro" contêm o código do erro
}

I think it would be more interesting to do it without Val, if you want help you have to give more details.