storage.html

<script>

  function fillCache() {
    caches.open('test').then(function (cache) {
      for (var i = 0; i < 30000; i++) {
        cache.put('https://example.com/probably-crash-' + i, new Response('ok')).then(function() {
          filled.innerText = i;
        })
      }
    });
  }

  function readCache() {
    caches.open('test').then(function (cache) {
      cache.keys().then(function(keys) {
        console.log('success')
      }).catch(function (e) {
        alert(e);
      });
    });
  }

</script>

<div>
Filling <span id="filled">...</span>
<button onclick="fillCache();readCache()">Crash!</button>