JavaScript 利用reduce 去掉对象数组中key值相同的对象 和 去重

let arr = [
  {"weight":10,"id":1},
  {"weight":20,"id":2},
  {"weight":30,"id":2},
  {"weight":40,"id":4},
  {"weight":50,"id":5}
];

let obj = {}
arr = arr.reduce((item, next) => {
  obj[next.id] ? '' : obj[next.id] = true && item.push(next)
  return item
}, [])
console.log(arr)

 

var arr1 = [3,4,4,5,5,1,1,4,7,8,9,9];
arr1 = arr1.reduce((item,next)=>{
    item.indexOf(next)>-1?'':item.push(next)
return item
},[]);
console.log(arr1)