JS判断页面是否为浏览器当前页

function currentPage() {

  var hiddenProperty = 'hidden' in document ? 'hidden' :

    'webkitHidden' in document ? 'webkitHidden' :

      'mozHidden' in document ? 'mozHidden' :

        null;

  var visibilityChangeEvent = hiddenProperty.replace(/hidden/i, 'visibilitychange');

  var onVisibilityChange = function () {

    if (!document[hiddenProperty]) {

      console.log('页面激活');

    } else {

      console.log('页面非激活')

    }

  }

  document.addEventListener(visibilityChangeEvent, onVisibilityChange);

}