前端传递参数时form-data和json的区别详解

const formData = new FormData();
formData.append('username', 'John');
formData.append('avatar', file); // 上传文件

// 发送请求
axios.post('/api/endpoint', formData, {
  headers: {
    'Content-Type': 'multipart/form-data'
  }
});

const data = {
  username: 'John',
  age: 25
};

// 发送请求
axios.post('/api/endpoint', JSON.stringify(data), {
  headers: {
    'Content-Type': 'application/json'
  }
});

function transformToJson(form) {
  var jsonData = {};
  var formData = new FormData(form);
  var formArray = $(form).serializeArray();

  $.each(formArray, function() {
    var dataType = $("select\[name='" + this.name + "'\]").attr("data-type");
    var value = this.value;

    if (value == "无" || value == "") {
      value = null;
    }

    if (jsonData\[this.name\]) {
      if (!jsonData\[this.name\].push) {
        jsonData\[this.name\] = \[jsonData\[this.name\]\];
      }
      jsonData\[this.name\].push(value || '');
    } else {
      if (dataType == 'array') {
        jsonData\[this.name\] = \[\];
        jsonData\[this.name\].push(value || '');
      } else {
        jsonData\[this.name\] = value || '';
      }
    }
  });

  return jsonData;
}