Here is another way, without jQuery:
<script>
function update(){
let updateValue = document.getElementById("name").value;
document.getElementById("name2").value = updateValue;
}
</script>
<form action="/new" method="POST" >
<input list="name" type="text" name="name" id="name" onchange="update()">
<datalist id="name">
<option value="Hello">
<option value="Hi">
</datalist>
<button>Submit</button>
</form>
<form action="/new1" method="POST">
<input type="text" name="name" id="name2" value="name" >
</form>
1
solved How to copy the selected value from one form input field to another form input field