场景：
1、把单一数字，根据某一个字段作为键值重组新的数组。
2、使用vue的$set函数$set(数组,键,值 )

//原始数组
oArr=[
{id: 1, type: 2, title:'aaa'},
{id: 2, type: 2, title:'aaa'}
{id: 3, type: 2, title:'bbb'},
{id: 4, type: 2, title:'aaa'}
];

//处理
var newArr={};
oArr.map(item => {
		if (!newArr[item.title]) {//空键值处理
			this.$set(newArr, item.title, [])
		}
		newArr[item.title].push(item)
	})
	console.info(newArr)

获得新数组：

newArr={
	aaa:[
		{id: 1, type: 2, title:'aaa'},
		{id: 2, type: 2, title:'aaa'}
		{id: 4, type: 2, title:'aaa'}
	]
	bbb:[
		{id: 3, type: 2, title:'bbb'},
	]
};

终了~