JSFiddle - React, Tailwind, and code Playground

HTML

<select id="myselect">
    <option>Please select...</option>
    <option>Pre existing options...</option>
</select>

JavaScript

var result = {
	main: [{
    	id: 10
    },{
    	id: 20
    },{
    	id: 30
    },{
    	id: 40
    },{
    	id: 50
    }]
}

var html = '';
$.each(result.main, function(result, value) {
    html += '<option value="' + value.id + '">' + value.id + '</option>'
});
$('#myselect').append(html).val(result.main[0].id);