create unique id with javascript

Question

I have a form where a user can add multiple select boxes for multiple cities. The problem is that each newly generated select box needs to have a unique id. Can this be done is JavaScript?

Here is the part of the form for selecting cities. Also note that I'm using some PHP to fill in the cities when a specific state is selected.

<form id="form" name="form" method="post" action="citySelect.php">
<select id="state" name="state" onchange="getCity()">
    <option></option>
    <option value="1">cali</option>
    <option value="2">arizona</option>
    <option value="3">texas</option>
</select>
<select id="city" name="city" style="width:100px">
    
</select>

    <br/>
</form>

Here is the JavaScript:

$("#bt").click(function() {

$("#form").append(
       "<select id='state' name='state' onchange='getCity()'>
           <option></option>
           <option value='1'>cali</option>
           <option value='2'>arizona</option>
           <option value='3'>texas</option>
        </select>
        <select id='city' name='city' style='width:100px'></select><br/>"
     );
});

Answer 1

var id = "id" + Math.random().toString(16).slice(2) 

Answer 2

another way it to use the millisecond timer:

var uniq = 'id' + (new Date()).getTime();

Answer 3

const uid = function(){
    return Date.now().toString(36) + Math.random().toString(36).substr(2);
}

This Function generates very unique IDs that are sorted by its generated Date. Also useable for IDs in Databases.