vue中变量名前加三个点代表什么意思

https://segmentfault.com/q/1010000020240597 

row: {
                ...item
            },

var a = {
  name: '张三',
  age: 25
}

var b = {
  job: 'web前端',
  ...a
}

// 相当于
var c = {
  job: 'web前端',
  name: '张三',
  age: 25
}