每天get几个JavaScript小技巧(四)

判断图片加载完成

const imgLoadAll = function (arr, callback) { //图片加载
  let arrImg = []
  for (let i = 0; i < arr.length; i++) {
    let img = new Image()
    img.src = arr[i]
    img.onload = function() {
      arrImg.push(this)
      if(arrImg.length === arr.length) {
        callback && callback()
      }
    }
  }
}

音频完成加载操作

const loadAudio = function(src, callback) {
  let audio = new Audio(src)
  audio.onloadedmetadata = callback
  audio.src = src
}

浏览器是否支持Webp格式

const isSupportWebp = function () {
  return !![].map &&
    document.createElement('canvas').toDataURL('image/webp').indexOf('data:image/webp') == 0;
}