javascript canvas 取得图片的base64字符串

* 到https://www.baidu.com

* 浏览器控制台粘贴

function getBase64Image(img) {
    var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;
    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0, img.width, img.height);
    var ext = img.src.substring(img.src.lastIndexOf(".") + 1).toLowerCase();    
    return canvas.toDataURL("image/" + ext);
}

var image = new Image();
image.onload = function() {
    var data = getBase64Image(this);
    console.log(data);
    var newImage = new Image();
    newImage.src = data;
    document.body.append(newImage);
    newImage.style.zIndex = 3;
    newImage.style.position = "fixed";
    newImage.style.left = 0;
    newImage.style.top = 0;
}
image.src = "https://www.baidu.com/img/bd_logo1.png";