How to Remove All Duplicates from an Array of Objects?

Javascript Arrays Object Duplicates

If you have an object that contains an array of objects and you want to remove all duplicates from the array, there are multiple methods you can use in JavaScript. In this article, we will explore some of the best and most efficient ways to accomplish this task.

Method 1: Using Set

One of the simplest ways to remove duplicates from an array is by using a Set. A Set is a JavaScript object that allows you to store unique values of any type. Here's how you can utilize a Set to remove duplicates from an array of objects: 


const arr = [
  {place: "here", name: "stuff"},
  {place: "there", name: "morestuff"},
  {place: "there", name: "morestuff"}
];

const uniqueArr = [...new Set(arr.map(obj => JSON.stringify(obj)))].map(str => JSON.parse(str));

console.log(uniqueArr);

In this code snippet, we first use the map function to convert each object in the array to a JSON string using JSON.stringify(obj). Then, we create a new Set from the resulting array of strings.

Next, we use the spread operator (...) to convert the Set back into an array. Since the spread operator only works on iterable objects, we need to use the array prototype map function to map each string back to its original object using JSON.parse(str).

Finally, we log the unique array of objects to the console.

Method 2: Using forEach and filter

Another approach to remove duplicates from an array of objects is by using the forEach and filter methods. This method is slightly more concise and may be easier to understand for some developers. Here's an example: 


const arr = [
  {place: "here", name: "stuff"},
  {place: "there", name: "morestuff"},
  {place: "there", name: "morestuff"}
];

const uniqueArr = [];

arr.forEach(obj => {
  const hasDuplicate = uniqueArr.some(uniqueObj => uniqueObj.place === obj.place && uniqueObj.name === obj.name);
  if (!hasDuplicate) {
    uniqueArr.push(obj);
  }
});

console.log(uniqueArr);

In this code snippet, we first initialize an empty array called uniqueArr. Then, we iterate over each object in the original array using the forEach method.

For each object, we use the some method to check if there is already an object in the uniqueArr with the same place and name properties. If a duplicate is found, hasDuplicate will be true.

If there is no duplicate, we push the object into the uniqueArr array.

Method 3: Using reduce

The reduce method is another powerful tool in JavaScript that can be utilized to remove duplicates from an array. Here's how you can use reduce to achieve this: 


const arr = [
  {place: "here", name: "stuff"},
  {place: "there", name: "morestuff"},
  {place: "there", name: "morestuff"}
];

const uniqueArr = arr.reduce((accumulator, obj) => {
  const existingObj = accumulator.find(item => item.place === obj.place && item.name === obj.name);
  if (!existingObj) {
    accumulator.push(obj);
  }
  return accumulator;
}, []);

console.log(uniqueArr);

In the code snippet above, we use the reduce method on the original array, starting with an initial empty accumulator array ([]).

For each object in the array, we use the find method to check if there is already an object in the accumulator array with the same place and name properties. If no object is found, we push the current object into the accumulator array.

Finally, we return the accumulator array, which contains only the unique objects, to the uniqueArr variable.

Method 4: Using Lodash

If you prefer to use a library, such as Lodash, you can take advantage of its built-in functions to easily remove duplicates from an array of objects. Here's an example: 


const arr = [
  {place: "here", name: "stuff"},
  {place: "there", name: "morestuff"},
  {place: "there", name: "morestuff"}
];

const uniqueArr = _.uniqWith(arr, _.isEqual);

console.log(uniqueArr);

In this code snippet, we first import the Lodash library (assuming it is already installed and available in your project). Then, we use the uniqWith function to remove duplicates from the array.

The uniqWith function takes two arguments: the original array and a function that defines the comparison logic. In this case, we use _.isEqual to compare objects for equality.

Finally, we log the unique array of objects to the console.

Conclusion

Removing duplicates from an array of objects in JavaScript can be achieved using various methods. Whether you choose to use the native Set object, the forEach and filter methods, the reduce method, or a library like Lodash, the goal is to eliminate redundant objects and keep only the unique ones.

As with any problem in programming, the best approach may vary depending on your specific requirements and constraints. It is essential to consider factors such as performance, readability, and the overall structure of your code.

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