CODEWITHSUNDEEP
node.jsjson
wanderors
wanderors

Reputation: 2292

nodejs read json and ignore the first occurrence of duplicate value

I have a json data like this.

[{
    "name": "Peter",
    "age": 30,
    "hair color": "brown"
}, {
    "name": "Steve",
    "age": 55,
    "hair color": "blonde"
}, {
    "name": "Steve",
    "age": 25,
    "hair color": "black"
}]

My code it does is, It will identify the duplicate and remove the second occurrence.

The code is :

var qdata = [{
    "name": "Peter",
    "age": 30,
    "hair color": "brown"
}, {
    "name": "Steve",
    "age": 55,
    "hair color": "blonde"
}, {
    "name": "Steve",
    "age": 25,
    "hair color": "black"
}]
 data = qdata.filter((obj, pos, arr) => {
            return arr.map(mapObj =>
                  mapObj.name).indexOf(obj.name) == pos;
            });
          console.log(data);

Output will be :

[
  { name: 'Peter', age: 30, 'hair color': 'brown' },
  { name: 'Steve', age: 55, 'hair color': 'blonde' }
]

Here it deletes the second occurrence and keeps the first one, But what I would like to get is remove the first occurrence and keep the second one

[
      { name: 'Peter', age: 30, 'hair color': 'brown' },
      { name: 'Steve', age: 25, 'hair color': 'black' }
    ]

How can I do that ? Please help

Upvotes: 0

Views: 60

Answers (1)

Rajeshwar
Rajeshwar

Reputation: 2509

You can simply reverse the array and do what you want and reverse the result to match with your expected result.

qdata.reverse();

data = qdata.filter((obj, pos, arr) => {
  return arr.map(mapObj => mapObj.name).indexOf(obj.name) == pos;
});

console.log(data.reverse());

if you don't want to do that you can use the below code to get desired result.

data = [];

qdata.map((i) => {
  index = data.findIndex((u) => u.name === i.name);
  if (index >= 0) {
    data.splice(index, 1, i);
  } else {
    data.push(i);
  }
});

console.log(data);

Upvotes: 1

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