JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<form id="User" name="User" method="post" enctype="multipart/form-data" action="index">
    <select data-placeholder="Choose College Name" name="college[]" class="chosen-select" id="college" multiple tabindex="4">
        <option value=""></option>
        <option value="1">abc</option>
        <option value="2">abc1</option>
    </select> 
    <input id="dosubmit" type="submit" value="Submit" />
</form>

JavaScript

$('#User').submit(function(e){
    var col = $('#college').val();
    if ( col==null || col=='' || col=='Please choose one:' ){
        $('#college').css('background','yellow').focus();
        return false;
    }else{
        $('#college').css('background','transparent');
        alert('Form submitted');
        //continue to submit the form - but not now
        return false;
    }
});