title: AngularJS: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
body: <p>So I had this directive:</p>
  
  <pre><code>app.directive('customDropdown', function() {
      return {
          restrict: 'E',
          templateUrl: '/static/templates/directive_templates/customdropdown.html',
          link: function(scope, element, attrs) {
              console.log(attrs.custom-class);
          }
      }
  })
  </code></pre>
  
  <p>Markup:</p>
  
  <pre><code>&lt;custom-dropdown custom-class="custom-select-menu"&gt;
  
  &lt;/custom-dropdown&gt;
  </code></pre>
  
  <p>But, due to <code>console.log(attrs.custom-class)</code> I get the error mentioned in the question. It goes away when I change <code>custom-class</code> to just <code>custom</code>. Any idea why the error was popping up? Can't use hyphens?</p>