iscroll 被動事件偵聽器以提升滾動性能(ie not support)

isPassive.js

/**
 * iscroll 被動事件偵聽器以提升滾動性能(ie not support)
 * source code : https://github.com/cubiq/iscroll/blob/master/demos/demoUtils.js
 * MDN : https://developer.mozilla.org/zh-CN/docs/Web/API/EventTarget/addEventListener#option%E6%94%AF%E6%8C%81%E7%9A%84%E5%AE%89%E5%85%A8%E6%A3%80%E6%B5%8B
 * passive google article : https://developers.google.com/web/tools/lighthouse/audits/passive-event-listeners?hl=zh-tw
 */
function isPassive () {
  var passiveSupported = false

  try {
    var options = Object.defineProperty({}, 'passive', {
      get: function () {
        passiveSupported = true
      }
    })
    window.addEventListener('test', null, options)
  } catch (err) { }

  return passiveSupported
}