v-LazyLoad

const LazyLoad = { // install方法 install(Vue, options) { const defaultSrc = options.default Vue.directive('lazy', { bind(el, binding) { LazyLoad.init(el, binding.value, defaultSrc) }, inserted(el) { if (IntersectionObserver) { LazyLoad.observe(el) } else { LazyLoad.listenerScroll(el) } }, }) }, // 初始化 init(el, val, def) { el.setAttribute('data-src', val) el.setAttribute('src', def) }, // 利用IntersectionObserver监听el observe(el) { var io = new IntersectionObserver((entries) => { const realSrc = el.dataset.src if (entries[0].isIntersecting) { if (realSrc) { el.src = realSrc el.removeAttribute('data-src') } } }) io.observe(el) }, // 监听scroll事件 listenerScroll(el) { const handler = LazyLoad.throttle(LazyLoad.load, 300) LazyLoad.load(el) window.addEventListener('scroll', () => { handler(el) }) }, // 加载真实图片 load(el) { const windowHeight = document.documentElement.clientHeight const elTop = el.getBoundingClientRect().top const elBtm = el.getBoundingClientRect().bottom const realSrc = el.dataset.src if (elTop - windowHeight < 0 && elBtm > 0) { if (realSrc) { el.src = realSrc el.removeAttribute('data-src') } } }, // 节流 throttle(fn, delay) { let timer let prevTime return function (...args) { const currTime = Date.now() const context = this if (!prevTime) prevTime = currTime clearTimeout(timer)

  if (currTime - prevTime > delay) {
    prevTime = currTime
    fn.apply(context, args)
    clearTimeout(timer)
    return
  }

  timer = setTimeout(function () {
    prevTime = Date.now()
    timer = null
    fn.apply(context, args)
  }, delay)
}

}, }

export default LazyLoad