[Malleys]

<div class="block">1</div>
<div class="block">2</div>
<div class="block">3</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js"></script>
<script>
// $('.checkshadow').click(function() {
//       if($(this).is('.check')) {
//           $(this).removeClass('check');
//       } else {
//           $(this).addClass('check');
//       }
//   });

$(".block")
  .html("<a>ALL</a>" + "<a>Link</a>".repeat(100))
  .on("click", "a", function(event) {
      $(this).toggleClass("check")
  })
  .on("click", ":contains('ALL')", function(event) {
      $(this).closest(".block").find("a").removeClass("check");
  });

</script><style>
body {
  display: flex;
}

.block {
  background: deeppink;
  margin: 1em;
  padding: 1em;
}

.block a {
  display: inline-block;
  background: white;
  padding: 1em;
  margin: .1em;
}

.block a.check {
  background: red;
}
</style>

Простите за ужасный вид