// 对图片进行压缩 
    function compress(imgPath) {
        var image = new Image();
        //新建一个img标签（还没嵌入DOM节点) 
        image.src = imgPath;
        image.onload = function() {
            var canvas = document.createElement('canvas');
            var    context = canvas.getContext('2d');
            var    imageWidth = image.width / 3;
                //压缩后图片的大小 
            var    imageHeight = image.height / 3;
            var data = '';
            canvas.width = imageWidth; 
            canvas.height = imageHeight;
            context.drawImage(image, 0, 0, imageWidth, imageHeight);
            data = canvas.toDataURL('image/jpeg')
            //压缩完成 
            $(".srcDiscernImg").attr("src", data);
            console.log("渲染。。。。");
        }
    }