How to Efficiently Deduplicate Arrays of Objects Based on Specific Properties?

Efficient Deduplication of Arrays of Objects

Removing duplicate objects from arrays can be crucial for data integrity and performance optimization. This article explores effective methods to eliminate duplicates from arrays containing objects.

Problem:

Consider an object with an array of nested objects. The goal is to remove duplicate objects based on their "place" and "name" properties.

obj = {};

obj.arr = new Array();

obj.arr.push({place: "here", name: "stuff"});
obj.arr.push({place: "there", name: "morestuff"});
obj.arr.push({place: "there", name: "morestuff"});

Solution:

Method 1: ES6 Filtering with Array.filter and Array.findIndex

obj.arr = obj.arr.filter((value, index, self) =>
  index === self.findIndex((t) =>
    t.place === value.place && t.name === value.name
  )
);

This method leverages Array.filter and Array.findIndex to iterate through the array and identify duplicates. It returns only the unique objects, preserving both properties.

Method 2: Generic Solution with JSON.stringify

const uniqueArray = obj.arr.filter((value, index) => {
  const _value = JSON.stringify(value);
  return index === obj.arr.findIndex((obj) => {
    return JSON.stringify(obj) === _value;
  });
});

This approach compares the JSON representation of objects to detect duplicates. It's a generic solution that can accommodate objects with any property structure.

Method 3: Using Custom Property Equality Comparison

const isPropValuesEqual = (subject, target, propNames) =>
  propNames.every((propName) => subject[propName] === target[propName]);

const getUniqueItemsByProperties = (items, propNames) =>
  items.filter((item, index, array) =>
    index === array.findIndex((foundItem) => isPropValuesEqual(foundItem, item, propNames))
  );

This method allows for more customized property comparison. It uses a callback function to determine property equality and returns a unique set of objects based on the specified properties.

Explanation:

The key to deduplication is finding duplicates and excluding them from the result. The findIndex function helps identify the first instance of an object with specific properties, while filter removes duplicates that occur subsequently.

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