图片转化成base64编码

var img = "imgurl";//imgurl 就是你的图片路径  

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();
     var dataURL = canvas.toDataURL("image/"+ext,0-1);(0-1　　　　表示图片的质量)
     return dataURL;
}  

var image = new Image();
image.src = img;
image.onload = function(){
  var base64 = getBase64Image(image);
  console.log(base64);
}