Operation of the array of objects

Merge array 
this.multipleSelection.forEach ((Val) => { 
  this.returnData.push (Val) 
}) 


based on the unique identification of the array of objects to heavy

let hash = {};
this.returnData = this.returnData.reduce((preVal, curVal) => {
  hash[curVal.skuId] ? '' : hash[curVal.skuId] = true && preVal.push(curVal);
  return preVal
}, [])