canvas实现压缩图片的代码示例

// 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。。。。");        }    }