vue this.$set

data() {
	str: '111',
	arr: [1, 2, 7, 4],
	obj: {
		name: 'lin',
		age: 18
	}
}

this.$set(this, 'str', 'aaa')			// aaa

this.$set(this.arr, 2, 3)				//  1, 2, 3, 4    修改

this.$set(this.arr, this.arr.length, 5)    // 1, 2, 3, 4, 5    添加

this.$set(this.obj, 'age', 20)			// {name: 'lin', age: 20}    修改

this.$set(this.obj, 'sex', 'female')    // {name: 'lin', age: 20, 'sex': 'female'}    添加