封装一个图片预加载方法

方法：

const imgSrcQueue: Array<HTMLImageElement> = [];

export function preloadImageList(names) {
  return new Promise((resolve) => {
    let n = 0,
      img,
      imgs = {};
    names.forEach(function (name) {
      img = new Image();
      imgSrcQueue.push(img);
      img.onload = img.onerror = (function (name, img) {
        return function () {
          imgs[name] = img;
          ++n === names.length && resolve(imgs);
        };
      })(name, img);
      img.src = name;
    });
  });
}

使用：

const loadingImageList = ['https://img.alicdn.com/imgextra/i3/O1CN01aDYIho1DM6MYWMeVD_!!6000000000201-2-tps-2405-1089.png']

useEffect(() => {
      preloadImageList(loadingImageList);
  }, []);