js-下载图片

fucntion downloadIamge(imgsrc, name) {
    
	let image = new Image();
	// 解决跨域 Canvas 污染问题
	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"); //得到图片的base64编码数据
		let a = document.createElement("a"); // 生成一个a元素
		let event = new MouseEvent("click"); // 创建一个单击事件
		a.download = name || "photo"; // 设置图片名称
		a.href = url; // 将生成的URL设置为a.href属性
		a.dispatchEvent(event); // 触发a的单击事件
	};
	image.src = imgsrc;
}

// 兼容性不好,QQ浏览器不行, 64版本谷歌都不行

function downloadImg(src, name){
    
    let canvas = document.createElement('canvas'),
        img = document.createElement('img');

    img.src = src;
    img.setAttribute("crossOrigin",'Anonymous')

    img.onload = function(e) {
    
        canvas.width = img.width;
        canvas.height = img.height;
        var context = canvas.getContext('2d');

        context.drawImage(img, 0, 0, img.width, img.height);
        canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height);
        canvas.toBlob( (blob) => {
    
            let link = document.createElement('a');
            link.href = window.URL.createObjectURL(blob);
            link.download = '文件名'; 
            link.click();
        }, "image/jpg");
    }
}

1. data: 协议 base64?
2. blob: 协议?