修改原数组对象特定位置里的数据

原数组对象a如：

//对象a
[{
	"num": "20181101",
	"name": "张三",
	"age": 12
}, {
	"num": "20181102",
	"name": "李四",
	"age": 22
}]

操作：在数组对象a中找到num为20181102的对象，添加字段sex，并赋值女。js代码如下：

const newData = a;
let num = "20181102";
const target = newData.filter((item,index) => num === item.num)[0];
if (target) {
   target['sex'] = "女";
   console.log("新的数据newData:",newData);
}