canvas 渲染网页中可显示的图片跨域

1、如下代码

 let img = new Image();
            img.setAttribute("crossOrigin",'anonymous');
            img.src = url+ `?timestamp= ${+new Date()}`;  //谷歌浏览器下可能会用缓存，避免用缓存增加时间戳防止提示跨域
            img.onload = function(){
                let canvas = document.createElement('canvas');
                canvas.width = img.width;
                canvas.height = img.height;
                let ctx = canvas.getContext('2d');
                ctx.drawImage(img,0,0,canvas.width,canvas.height)
                let base = canvas.toDataURL('image/jpeg',0.95)
                resolve(base)
            }
            img.onerror=function(){
                message.warning('转换图片失败,用火狐浏览器')
                resolve()
            }