selectAll.change(function(){

  let isSelectAll = selectAll.is(':checked');

  if(isSelectAll){

    deselectAllLabel.show();

    selectAllLabel.hide();

    //langs.prop('checked', true);

  }else{

    deselectAllLabel.hide();

    selectAllLabel.show();

    //langs.prop('checked', false)

  }

  langs.prop('checked', isSelectAll);

});

invertSelect.click(function(){

  for(let i = 0; i < langs.length; i++){

    let lang = $(langs.get(i));

    let isLangChecked = lang.is(':checked');

    lang.prop('checked', !isLangChecked);

  }

  langs.change();

});

langs.change(function(){ 

  let isAllChecked = true;

  for(let i = 0; i < langs.length; i++){

    let lang = $(langs.get(i));

    let isLangChecked = lang.is(':checked');

    if(!isLangChecked){

      isAllChecked = false;

      break;

    }

  }

  if(isAllChecked){

    selectAll.prop('checked', true);

    deselectAllLabel.show();

    selectAllLabel.hide();

  }else{

    selectAll.prop('checked', false);

    deselectAllLabel.hide();

    selectAllLabel.show();

  }

})