图片尺寸比例和大小校验

function getImageFileInfo(file) {
  return new Promise((resolve, reject) => {
    let reader = new FileReader();
    reader.onerror = (e) => {
      console.error('读取异常')
      reject(false)
    }
    reader.onloadend = (e) => {
      let image = new Image();
      image.src = e.target.result;
      image.onload = () => resolve([image, e.target.result])
    }
    reader.readAsDataURL(file);
  })
}
function getImageSizeCheck(image, option) {
  function gcd(a, b) {
    if (b == 0) return a;
    return gcd(b, a % b)
  }
  const { width = 1920, height = 1080, size = 10240, ratio = 0.15 } = option || {};
  const { width: w, height: h, size: s } = image;
  const imgRatio = w / h; // 图片尺寸比例
  const optRatio = width / height; // 预设尺寸比例 
  let msg = '';
  if (size < s) msg = `图片需小于${size}KB,`;
  if (imgRatio > optRatio + ratio && imgRatio < optRatio - ratio) msg += `图片尺寸需符合${w}*${h}或${w / gys(w, h)}:${h / gys(w, h)}比例`;
  if (msg) throw new Error(msg);
  return true;
}
function gys(...args) {
  const [item, ...rest] = args;
  if (rest.length < 1) return a;
  if (rest.length === 1) {
    let a = item, b = rest[0];
    while (a > 0 && b > 0 && a != b) {
      if (a > b) a -= b;
      else b -= a;
    }
    return a
  }
  return gys(item, gys(...rest))
}
const [image, img] = await getImageFileInfo(file);
getImageSizeCheck(image, { size: 1024, width: 1920, height: 1080 })