js图片转base64格式

getBase64 = (file) = >{return new Promise((resolve, reject) => {      const reader = new FileReader()      let fileResult = ''      reader.readAsDataURL(file)      reader.onload = () => { fileResult = reader.result      }      reader.onerror = (error) => { reject(error)      }      reader.onloadend = () => { resolve(fileResult)      }    })}// 调用let base64Data = nullgetBase64(file).then((response)=>{base64Data = response}).catch((error)=>{console.error(error)})