formData传数组作为参数

const formData = new FormData()
let arr=[{a:1,c:3},{a:2,c:4}];
for(let i=0;i<arr.length;i++){
   for(let key in arr[i]){
     //假设这个数组对应的字段为box
       formData.append(`box[${i}][${key}]`,arr[i][key])          
  }
}