need help in javascript snippet-CodePudding

From the following snippet, I have to iterate through all receipts, get the receipt number, and add that object to the JSON. But I am getting the same receipt in two JSON. Where am I missing? Can anyone help? Thanks in advance.

const shopList = [];
const shop = {
"shopNumber": "2242461",
"shopDate": "2020-06-13T00:00:00.000-05:00",
"shopAmount": "100",
"shopBank": "HDFC",
"shopDetails": {
    "shopNumber": "1242461",
    "shopDate": "2020-06-13T00:00:00.000-05:00",
    "shopBank": "HDFC",
    "shopAmount": "100"
},
"receiptDetails": [{
        "userNumber": "115729",
        "receiptNumber": "temp1"
    },
    {
        "userNumber": "115726",
        "receiptNumber": "temp2"
    }
]

};
 shop.receiptDetails.forEach((receipt) => {
var temp = shop.shopDetails;
temp.receiptNumber = receipt.receiptNumber;
shopList.push({
    shopNumber: shop.shopNumber,
    userNumber: Number(receipt.userNumber),
    receiptNumber: receipt.receiptNumber,
    shopDetails: temp,
    isSync: 0
});
});
shopList.forEach((receipt) => {
console.log(receipt);
});

I am getting output as

{
shopNumber: '2242461',
userNumber: 115729,
receiptNumber: 'temp1',
shopDetails: {
    shopNumber: '1242461',
    shopDate: '2020-06-13T00:00:00.000-05:00',
    shopBank: 'HDFC',
    shopAmount: '100',
    receiptNumber: 'temp2' ----**this should be temp1**
},
isSync: 0
} {
shopNumber: '2242461',
userNumber: 115726,
receiptNumber: 'temp2',
shopDetails: {
    shopNumber: '1242461',
    shopDate: '2020-06-13T00:00:00.000-05:00',
    shopBank: 'HDFC',
    shopAmount: '100',
    receiptNumber: 'temp2'    
},
isSync: 0
}

CodePudding user response：

That is because temp is a reference to shop.shopDetails. Objects in JavaScript are passed by reference, when you assign the temp.receiptNumber, it equals to shop.shopDetails.receiptNumber - Therefore, the temp value that you get in the next iterations is carried over from the last iteration

Read more about how javascript objects variable works in this answer, I think it explains it very well.

As for your approach, one of many ways you could solve it is to clone the object of shop.shopDetails in each iteration, therefore you'll get a new object instead.

E.g.

const shopList = [];
const shop = {
    "shopNumber": "2242461",
    "shopDate": "2020-06-13T00:00:00.000-05:00",
    "shopAmount": "100",
    "shopBank": "HDFC",
    "shopDetails": {
        "shopNumber": "1242461",
        "shopDate": "2020-06-13T00:00:00.000-05:00",
        "shopBank": "HDFC",
        "shopAmount": "100"
    },
    "receiptDetails": [{
        "userNumber": "115729",
        "receiptNumber": "temp1"
    },
    {
        "userNumber": "115726",
        "receiptNumber": "temp2"
    }]
};

shop.receiptDetails.forEach((receipt) => {
    var temp = {...shop.shopDetails}; // This is to clone an object, there are other ways than this.
    temp.receiptNumber = receipt.receiptNumber;
    shopList.push({
        shopNumber: shop.shopNumber,
        userNumber: Number(receipt.userNumber),
        receiptNumber: receipt.receiptNumber,
        shopDetails: temp,
        isSync: 0
    });
});

shopList.forEach((receipt) => {
    console.log(receipt);
});

CodePudding user response：

These two lines are causing the duplicate receipt number since you are essentially adding the same JSON object to the shopList. Only the last update remains.

var temp = shop.shopDetails;
temp.receiptNumber = receipt.receiptNumber;

I recommend you to clone shopDetails to which you add receiptNumber.

var temp = JSON.parse(JSON.stringify(shop.shopDetails));

Here is your modified code:

const shopList = [];
const shop = {
  "shopNumber": "2242461",
  "shopDate": "2020-06-13T00:00:00.000-05:00",
  "shopAmount": "100",
  "shopBank": "HDFC",
  "shopDetails": {
    "shopNumber": "1242461",
    "shopDate": "2020-06-13T00:00:00.000-05:00",
    "shopBank": "HDFC",
    "shopAmount": "100"
  },
  "receiptDetails": [{
    "userNumber": "115729",
    "receiptNumber": "temp1"
  },
  {
    "userNumber": "115726",
    "receiptNumber": "temp2"
  }
  ]

};
shop.receiptDetails.forEach((receipt) => {
  var temp = JSON.parse(JSON.stringify(shop.shopDetails));
  temp.receiptNumber = receipt.receiptNumber;
  shopList.push({
    shopNumber: shop.shopNumber,
    userNumber: Number(receipt.userNumber),
    receiptNumber: receipt.receiptNumber,
    shopDetails: temp,
    isSync: 0
  });
});
shopList.forEach((receipt) => {
  console.log(receipt);
});