根據圖檔url位址儲存至本地

downloadIamge(imgsrc, name) {//下載下傳圖檔位址和圖檔名
  let image = new Image();
  // 解決跨域 Canvas 污染問題
  image.setAttribute("crossOrigin", "anonymous");
  image.onload = function() {
    let canvas = document.createElement("canvas");
    canvas.width = image.width;
    canvas.height = image.height;
    let context = canvas.getContext("2d");
    context.drawImage(image, 0, 0, image.width, image.height);
    let url = canvas.toDataURL("image/png"); //得到圖檔的base64編碼資料
    let a = document.createElement("a"); // 生成一個a元素
    let event = new MouseEvent("click"); // 建立一個單擊事件
    a.download = name || "photo"; // 設定圖檔名稱
    a.href = url; // 将生成的URL設定為a.href屬性
    a.dispatchEvent(event); // 觸發a的單擊事件
  };
  image.src = imgsrc;
},