Set selected option of select box

I want to set a option that was selected previously to be displayed on page load. I tried it with the following code:

$("#gate").val('Gateway 2');

with

<select id="gate">
    <option value='null'>- choose -</option>
    <option value='gateway_1'>Gateway 1</option>
    <option value='gateway_2'>Gateway 2</option>
</select>

But this does not work. Any ideas?

This definitely should work. Here's a demo. Make sure you have placed your code into a $(document).ready:

$(function() {
    $("#gate").val('gateway_2');
});

$(document).ready(function() {
    $("#gate option[value='Gateway 2']").prop('selected', true);
    // you need to specify id of combo to set right combo, if more than one combo
});