Nested Select Field

Hello is there a better way to do this? I have a nested relationship and I want to update all select field based on the parent value. It is working but not on production server. Thanks

$('#selectProjecttype').on('change',function(){
    getprojSubtype($(this).val());  
    //sets the value of #selectProjectsubtype
                
    setTimeout(function(){
        getprojSpetype($('#selectProjectsubtype').val());
        //sets the value of #selectProjectspetype
    },600); 
            
    setTimeout(function(){
        getprojSpesubtype($('#selectProjectspetype').val());
        //sets the value of #selectProjectspesubtype
    },1200);
});