JSFiddle - React, Tailwind, and code Playground

HTML

<form action="form_action.php" method="Post">
<select id="select_id" name="cars[]" multiple >
    <option value="all" id="option_id">All</option>
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
    <option value="opel">Opel</option>
    <option value="audi">Audi</option>
</select>
<input type="submit">
</form>

JavaScript

$('#option_id').click(function(){
    if ($("#select_id option[value=all]:selected").length > 0){
        alert('all is selected');
    }
    else{
        //DO something if not selected
    }
    //$("#select_id option:selected").removeAttr("selected");           //Remove
    //$("#select_id option").attr('selected', 'selected');      //Add
});