Question

1. when a text box is on focus, how can I make a listen to a down and up arrow press?
2. how can I get the focus on an element using codes?

Update

I want this for an auto-complete search. It’s working; all I want now when the down arrow key is pressed while typing, the focus moves to the drop-down list.

Answer 1

You could subscribe to the onkeydown event:

<input type="text" onkeydown="myFunc(this, event)" />

and inside the function check the key code to identify which key was pressed using the code:

function myFunc(sender, e) {
    var key = e.which ? e.which : e.keyCode;
    if (key === 38) {
        // up arrow was pressed
    }
}

and here’s a demo.

As far as setting the focus to a given element is concerned you could use the focus() function:

document.getElementById('id_of_element').focus();