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JavaScript Find Duplicate Values In Object

Last Updated : Jan 1, 2023

JavaScript Find Duplicate Values In Object

In this article we will show you the solution of JavaScript find duplicate values in object, in this article we will use different methods to use JavaScript to find duplicates in values in objects, the methods we are going to use here are – by using forloop, by using indexOf() method and by using reduce method.

Let’s check out below the steps by step guide.

Step By Step Guide On JavaScript Find Duplicate Values In Object :-

Method 1 -

At first, we are going to use for loop to find duplicate values in the object. Let’s look at the code.

<!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript finds duplicates in values in objects</title>
    <div id="container"></div>
    var alphabets=["a","a","c","b","e","b","b","c"]
    var duplicates=[]
    var temp_alphabets=[...alphabets].sort()
    for (var i=0;i<temp_alphabets.length;i++){
  1. First, we write <! DOCTYPE html> which we used as an instruction to the web browser about what version of HTML file is written in.
  2. Secondly, the <html> tag is used to indicate the beginning of an HTML document.
  3. As above now the <head> tag is used to contain information about the web page. In this tag, a <title> tag is used which helps us to specify a webpage title.
  4. Both <head> and <title> tags are Paired tags. So, both have </head> and </title> ending tags respectively.
  5. Thirdly, the <body> tag is used to define the webpage body. All the contents to show on the website are written here.
  6. Add the array.
  7. Then attach JavaScript by using the script tag
  8. Here first we have to duplicate the array
  9. Then use for loop to find duplicates.

Method 2 -

For the second method we are going to use the indexOf() method.

const array = [5, 9, 8, 9, 9, 2, 5];
const Find = array => array.filter((item, index) => arr.indexOf(item) !== index)
const duplicate= find(array);
  1. At first create a array
  2. Compare the index value to every value present in the array.
  3. If it is not match, store the value in separate array

Method 3 -

The third method we are going to use is one of the easiest methods to find duplicates. Let us understand the code.

let numbers=[6,7,4,7,3,9,9,6,3];
let elementCount=numbers.reduce((actualValue, val)=>{actualValue[val]=(actualValue[val]||0)+1;},{});
  1. Here we first create the array
  2. Then use reduce to find duplicates

Method 4 -

Last method used we are going to use the set() method. It is basically used to remove duplicate elements.

let Numbers=[6,7,4,7,3,9,9,6,3];
let newUniqueNumbers=[ Set(Numbers)];
  1. New Set(Numbers) contain all the values in array. It has to be unique.
  2. (…) is the spread operator
  3. The printed array doesn’t contain any of duplicate.

Conclusion :-

Lastly, in conclusion, here we can say that with the help of this article we find duplicates in the object's values.

I hope this article on JavaScript find duplicate values in object helps you and the steps and method mentioned above are easy to follow and implement.

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