npm install --save form-data
npm install --save axios
var fs = require('fs');
var axios = require('axios');

let data = fs.createReadStream(__dirname + '/../public/wx/coupon.png')
  let form = new FormData()
  form.append('type','image')
  form.append('media',data,'test.jpg')

  let getHeaders = (form=>{
    return
 
 new Promise((resolve,reject)=>{
      form.getLength((err,length)=>{
        if(err) reject(err)
        let headers = Object.assign({'Content-Length':length},form.getHeaders())
        resolve(headers)
      })
    })
  })

  getHeaders(form).then(headers=>{
    return axios.post(url,form,{headers:headers})
  })
 
.then((response)=>{
    console.log('圖片上傳成功-永久', response.data)
  }).catch(e=>{console.log('上傳圖片出錯-永久', e)})