How to remove duplicate items from array using javascript

Question

How can we remove duplicate items for the root of an array using javascript. The code below removes duplicate items that are nested in the array. I am hoping to remove the root duplicate.

let myItems = [{
    "Visible": true,
    "title": "Folder 1",
    "Children": [{
      "title": "item in folder",
      "IsGIF": false,
      "IsWeb": false
    }]
  },
  {
    "title": "item in folder",
    "IsGIF": false,
    "IsWeb": false
  }
]

let stringArray = myItems.map(JSON.stringify);
let uniqueStringArray = new Set(stringArray);
let uniqueArray = Array.from(uniqueStringArray, JSON.parse);

console.log(uniqueArray);

//outputs:


[{
    Visible: true,
    title: 'Folder 1',
    Children: [
      [Object]
    ]
  },
  {
    title: 'item in folder',
    IsGIF: false,
    IsWeb: false
  }
]

Hoping to get the following output:

[
  {
    "Visible": true,
    "title": "Folder 1",
    "Children": [
      {
        "title": "item in folder",
        "IsGIF": false,
        "IsWeb": false
      }
    ]
  }
]

Your algorithm seems to function fine: there are no duplicates in your array so it doesn't filter out any. How should the function know it needs to look in the `"Children"` key of the first object? Is there always an object with `"Children"` on your first entry? I feel like what you are trying to accomplish isn't yet accurately described in your question. — soimon, Jan 09 '21 at 19:30
Does this answer your question? [Remove duplicate values from JS array](https://stackoverflow.com/questions/9229645/remove-duplicate-values-from-js-array) — fdermishin, Jan 10 '21 at 06:06

score 0 · Answer 1 · answered Jan 10 '21 at 03:46

let arr = [0,2,1,6,5,3,4,4,2,2]
newArr = []
arr.sort()

for(let i = 0; i < arr.length; i++){
    if(arr[i] != arr[i+1]){
        newArr.push(arr[i])
    }
}

console.log(newArr)

You can do something like this. It will create a new array without duplicates.

score 0 · Accepted Answer · answered Jan 10 '21 at 04:35

you can traverse the array and track the items recursively.

const isSeen = (seen, item) => {
  return seen.some(s => s.title === item.title && s.IsWeb === item.IsWeb && s.IsGIF === item.IsGIF);
}

const traverse = (item, seen, parent) => {
  if (item.Children) {
    const obj = {};
    Object.keys(item).filter(
      k => k !== "Children"
    ).forEach(
      k => obj[k] = item[k]
    )
    obj.Children = [];
    parent.push(obj);
    item.Children.forEach(child => traverse(child, seen, obj.Children));
  } else if (!isSeen(seen, item)) {
    seen.push(item);
    parent.push(item);
  }
}


const removeDuplicates = (arr) => {
  const seen = [];
  const results = [];
  arr.forEach(item => traverse(item, seen, results));
  return results;
};


const result = removeDuplicates([{
    "Visible": true,
    "title": "Folder 1",
    "Children": [{
      "title": "item in folder",
      "IsGIF": false,
      "IsWeb": false
    }]
  },
  {
    "title": "item in folder",
    "IsGIF": false,
    "IsWeb": false
  }
]);

console.log(result);

How to remove duplicate items from array using javascript

2 Answers2