Removing Duplicate From Arrays

As we know that arrays are helpful in storing data in a sequence in the memory. But sometimes, there may be chances that we may store the same value or duplicate values in an array. Thus, we need to remove such duplicate values from the array. So, there are certain methods through which we can remove the elements from the array.

So, in this section, we will discuss those methods and will understand it with the help of the respective examples.

Generally, there are developers who need to make their code more accurate as well as optimized, and for such tasks, it is really needed to remove the duplicate elements from the array if any such element is present. Thus, there are certain methods that can help to remove duplicate values from the arrays.

So, let’s begin to discuss those methods one by one.

Using the filter () method

The filter () method is used for fetching the duplicate values from the array. The method creates a new array of elements in which we pass the specific condition, and if any such element returns false or fails out, it will not be a filtered array.

Let’s implement an example where we will filter out the array values using the filter () method. The example is shown below:

  <script>  var array=[“x”,”w”,”d”,”w”,”x”];  function filterDuplicates(new_array){  return new_array.filter((value,index) =>new_array.indexOf(value)===index);  }  console.log(filterDuplicates(array));  </script>  

Output:

Using Set () method

The Set () method is another method where a new Set is created or we can say a collection is created that stores unique values from the defined array. Below is the basic code implementation for the Set () method:

  <script>  var array=[“a”,”a”,”d”,”c”,”d”];  function setDuplicates(new_array){  return […new Set(new_array)]  }  console.log(setDuplicates(array));  </script>  

Output:

Using the reduce () method

The reduce () method is the type of method that reduce the elements of the array and then combine those values/elements of the array into a final array which is based on our specified reducer function.

Below is a code implementation for reducing the elements from the array:

  <script>  var array=[“you”,”me”,”I”,”you”,”me”,”I”];  function reduceDuplicates(new_array){  let collect=new_array.reduce(function (a,b){  if(a.indexOf(b)<0) a.push(b);  return a;  },[]);  return collect;  }  console.log(reduceDuplicates(array));  </script>  

Output:

Using forEach and includes () method

The includes () method is the one that returns false, if an element is not present in the given array and returns true if the element is present in the array. The forEach is the loop that will help us to iterate over the values present in the array.

Below is an example code that will help you understand the working of these methods to remove duplicate values from an array:

  <script>  var array=[“John”,”Merry”,”Ada”,”Merry”,”Michael”];  function duplicates(new_array){  let collect=[];  new_array.forEach(value=>{   if(!collect.includes(value))   {    collect.push(value)   }  });  return collect;  }  console.log(duplicates(array));  </script>  

Output:

Using indexOf () and push () methods

The indexOf () method and push () method can be used together in order to remove duplicate elements from the array and fetch out all the unqiue elements from it.

Below is an example code that will help you understand the working of indexOf () method with push () method:

  <script>  var array = [“red”,”yellow”,”blue”,”black”,”blue”];      function duplicates(new_array){          var collect = [];          for(i=0; i < new_array.length; i++){              if(collect.indexOf(new_array[i]) === -1) {                  collect.push(new_array[i]);              }          }          return collect;      }    console.log(duplicates(array));  </script>  

Output:

So, using these described methods we can filter and remove out the duplicate elements present in the array.

But if we need to remove duplicate objects from an array, we need to use the property name of the array. Similar to elements, these can be objects also which might be present duplicate in the array.

So, for removing duplicate objects from the given array, we can use the below code which is shown below:

  <script>      function removeDuplicates(new_array){          var collect = [];          for(var value of new_array){              if(collect.indexOf(value) === -1){                  collect.push(value);              }          }          return collect;      }      var colors = [“green”,”black”,”black”];  console.log(removeDuplicates(colors));  </script>  

Output:

Generally, such type of duplicate value elimination is required when we are working on any project especially. We need such method when we are a developer because every customer needs a perfect software or application that is well optimized, customized, friendly, and compatible so that the value of the organization may increase.

So, these are some of the methods that can be used by the developers while working on some projects using JavaScript.

Next TopicJavaScript insertBefore

Removing Duplicate From Arrays

Removing Duplicate From Arrays

Using the filter () method

Using Set () method

Using the reduce () method

Using forEach and includes () method

Using indexOf () and push () methods

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