formData实现图片上传

//1
var formData = new FormData(formDOM);


//2
var formData = new FormData();
formData.append(name , value , fileName)

var fileInput = document.querySelector('.input-file');
var files = fileInput.files

var formData = new FormData(); //创建formData对象

//判断数据 若有 则添加数据
if(files.length > 0){
  [].slice.call(files).forEach(function(value,index){
    formData.append('img' + index,value,value.name) //遍历添加数据
  })
}else {
  alert('请先选择图片');
  return false;
}

formidable = require('formidable'); //载入formidable
var express = require('express');
var app = express();

app.use(express.static('src',{   // 静态资源中间件
  setHeaders : function(res,path,stat){
    res.setHeader('Cache-Control', 'max-age=' + 6000);
  }
}));

app.post('/upload',function(req,res){
  var form = new formidable.IncomingForm();
  form.encoding = 'utf-8';
  form.uploadDir = './src/images';
  form.keepExtensions = true;

  form.parse(req,function(err,field,files){
    console.log(files);
  });
  res.send({
    'msg':'upload file'
  });
});

var server = app.listen(8081, function(){
  console.log('服务器已启动!');
});

      var httpDemo = new XMLHttpRequest(); //创建httprequest对象
      
      httpDemo.open('post','/upload',true); //初始化请求  post方式  接口  异步
      httpDemo.onload = function(e){
        console.log(e);
      }
      
      httpDemo.send(formData);  //发送请求

$.ajax({
url : '/upload',
type:'POST',
data: formData,
processData:false,
contentType:false,
success:function(data,textStatus,jqXHR){

},
error:function(jqXHR,textStatus,error){

}
})

        headers: {
          'Content-Type': 'multipart/form-data'
        },