图像下载.js

 var img = new Image();
 img.crossOrigin = 'Anonymous'; 
 img.onload = function () {
    var canvas = document.createElement('canvas');
    var ctx = canvas.getContext('2d');
    canvas.width = img.width;
    canvas.height = img.height;
    ctx.drawImage(img, 0, 0);
    var link = document.createElement('a');
    link.download = '图像名称.jpg';
    link.href = canvas.toDataURL('image/jpeg', 1.0);
    link.click();
    canvas = null;
 }
 img.src = '图像链接';