Why wont this work for me?

        <script type="text/javascript">
        'use strict';
      function supportsLocalStorage() {
        try {
      return "localStorage" in window && window["localStorage"] !== null 
        } catch(e) {
         return false;
      }
       }

        function getRecentSearches() {

      var searches = localStorage.getItem("recentSearches");
      if(searches){
        return JSON.parse(searches);

      } else {
        return [];
      }

       }

       function saveSearchString(str) {
      var searches = getRecentSearches();
      if (!str || searches.indexOf(str) > -1) {
        return false;
      }
      searches.push(str);
      localStorage.setItem("recentSearches", JSON.stringify(searches));
      return true; 
    }

    function removeSearches() {
      localStorage.removeItem("recentSearches");
    }

    // Create an li, given string contents, append to the supplied ul
    function appendListItem(listElement, string) {
      var listItemElement = document.createElement('LI');
      listItemElement.innerHTML = string;
      listElement.appendChild(listItemElement);
    }

    // Empty the contents of an element (ul)
    function clearList(listElement) {
      listElement.innerHTML = '';
    }

    window.onload = function() {
      if (supportsLocalStorage()) {
      var searchForm = document.getElementById('searchForm');
      var searchBar = document.getElementById('searchBar');
      var recentSearchList = document.getElementById('recentSearchList');
      var clearButton = document.getElementById('clearStorage');

      // Initialize display list
      var recentSearches = getRecentSearches();
      recentSearches.forEach(function(searchString) {
        appendListItem(recentSearchList,searchString);
      });

      // Set event handlers
      searchForm.addEventListener('submit', function(event) {
        event.preventDefault();
        var searchString = searchBar.value;
        if (saveSearchString(searchString)) {
          appendListItem(recentSearchList, searchString);
        }
      });

      clearButton.addEventListener('click', function(event) {
        removeSearches();
        clearList(recentSearchList);
      });
      }  
    };
     </script>