js canvas获取图片base64 dataUrl

function getImgBase64(path,callback){
	        var img = new Image();
	        img.src = path;

	        //图片加载完成后触发
	        img.onload = function(){
		        var canvas = document.createElement("canvas");
		        //获取绘画上下文
		        ctx = canvas.getContext("2d");

		        // 获取图片宽高
		        var imgWidth = img.width;
		        var imgHeight = img.height;

		        //设置画布宽高与图片宽高相同
		        canvas.width = imgWidth;
		        canvas.height = imgHeight;

		        //绘制图片
		        ctx.drawImage(img,0,0,imgWidth,imgHeight);
		        //图片展示的 data URI
		        var dataUrl = canvas.toDataURL(‘image/jpeg‘);
		        callback ? callback(dataUrl) : ‘‘;
	        };
        }

        getImgBase64(‘wood.png‘,function(dataUrl){
        	console.log(dataUrl);
        });