map.ts

    
/*

{
  "goodPackage": {
      "upsellList": [
        {
          "productCode": "product1"
        }
      ]
  },
  "betterPackage": {
      "upsellList": [
        {
          "productCode": "product2"
        }
      ]
  },
  "bestPackage": {
      "upsellList": [
        {
          "productCode": "product4"
        },
        {
          "productCode": "product3"
        }
      ]
}

}
*/

      const betterPackageCodes = this.hostingUpsellProducts.bestPackage.upsellList.map(prod => ([prod.productCode]));



/*
[
  {
    "name": "Prod 1",
    "productCode": "prod1",
  },
  {
    "name": "Prod 2",
    "productCode": "prod2",
  },
  {
    "name": "Product 3",
    "productCode": "prod3",
  }
]


*/
const selectedProducts = this.selectedProduct.map(prod => ({ productCode: prod.productCode })); // only get the prodcts 



   const  uniqueChannelID =  Number([...new Set(array)].join());

Remove Duplicates 

    const channelID = this.selectedProduct.map(prod => (prod.productId));
    const uniqueChannelID = Number([...new Set(channelID)].join());