网络图片转base64

let image = new Image()
arr.forEach((v1, i) => {
   let src = arr[i].replace(reg, '') // 清空所有双引号
   src = src.replace('src=http://img.jyeoo.net', '/third_image') //替换成nginx代理
   image.src = src
   image.crossOrigin = "*"
   image.onload = function() {
   let base64 = _this.getBase64Image(image)
   va.answer = va.answer.replace(v1, 'src="' + base64 + '"')
      }
   })

　　

// 网络图片转base64
      getBase64Image(img) {
        let canvas = document.createElement("canvas")
        canvas.width = img.width
        canvas.height = img.height
        let ctx = canvas.getContext("2d")
        ctx.drawImage(img, 0, 0, img.width, img.height)
        let dataURL = canvas.toDataURL("image/png")
        return dataURL
      }