add new array into an array from its array's subarray

I have an array,

let arr =[{SLNO:1, modules:[{id:1, name:DTR},{id:5, name:DYR},{id:8, name:YUR}]},
          {SLNO:2, modules:[{id:6, name:DTTR},{id:9, name:TTDYR}]}]

I want to add a new array into this array with modules IDs like,

let newarr =[{SLNO:1, modules:[{id:1, name:DTR},{id:5, name:DYR},{id:8, name:YUR}], mIDS:[1,5,8]},
          {SLNO:2, modules:[{id:6, name:DTTR},{id:9, name:TTDYR}],  mIDS:[6,9]}]

How to write like this?

>Solution :

You can use the forEach (documentation) and the map (documentation) methods

const arr = [{
    SLNO: 1,
    modules: [
       {id: 1,name: "DTR"},
       {id: 5, name: "DYR"},
       {id: 8,name: "YUR"}
    ]
  },
  {
    SLNO: 2,
    modules: [
       {id: 6,name: "DTTR"},
       {id: 9,name: "TTDYR"}
    ]
  }
]

arr.forEach(item => {
  const ids = item.modules.map(x => x.id)
  item.mIDS = ids
})

console.log(arr)