Se o valor da entrada for nulo, faça algo
if(document.getElementById("question").value.length == 0)
{
alert("empty")
}
Scary Salamander
if(document.getElementById("question").value.length == 0)
{
alert("empty")
}const inputFeilds = document.querySelectorAll("input");
const validInputs = Array.from(inputFeilds).filter( input => input.value !== "");
console.log(validInputs) //[array with valid inputs]<!-- check if any input field in "Form" is empty using JS -->
<script type="text/javascript">
function validateForm() {
var a = document.forms["Form"]["answer_a"].value;
var b = document.forms["Form"]["answer_b"].value;
if (!a || !b) {
alert("Please Fill All Required Fields");
return false;
}
}
</script>
<form method="post" name="Form" onsubmit="return validateForm()" action="">
<input type="text" name="answer_a" value="">
<input type="password" name="answer_b" value="password">
</form>