How can I remove duplicate values from an array in JavaScript?
Davide S

To remove duplicate values from an array in JavaScript, you can use various techniques, such as using Set, filter, or reduce. Here's a step-by-step approach for each method: 1. Using Set: - The Set object in JavaScript allows you to store unique values of any type. By converting the array to a Set and then converting it back to an array, duplicate values will be automatically removed.

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   function removeDuplicates(array) {
     return [...new Set(array)];
   }

In this example, theremoveDuplicates function takes anarray as a parameter. It converts the array to a Set using the spread operator (...) and thenew Set() constructor. The Set automatically eliminates duplicate values. Finally, it converts the Set back to an array using the spread operator. 2. Using filter: - Thefilter() method allows you to create a new array by filtering out duplicate values.

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   function removeDuplicates(array) {
     return array.filter((value, index, self) => self.indexOf(value) === index);
   }

Here, theremoveDuplicates function takes anarray as a parameter. It applies thefilter() method on the array, using an arrow function as the filter condition. The arrow function checks whether the current value's index (indexOf()) is equal to the index of the first occurrence of that value (index). If they are equal, the value is included in the filtered array. 3. Using reduce: - Thereduce() method allows you to iterate over the array and build a new array without duplicate values.

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   function removeDuplicates(array) {
     return array.reduce((accumulator, currentValue) => {
       if (!accumulator.includes(currentValue)) {
         accumulator.push(currentValue);
       }
       return accumulator;
     }, []);
   }

In this example, theremoveDuplicates function takes anarray as a parameter. It uses thereduce() method, initializing an empty array ([]) as the initial value. The reducer function checks if theaccumulator array already includes thecurrentValue. If it doesn't, thecurrentValue is added to theaccumulator usingpush(). The function returns theaccumulator at each iteration. Here's an example usage of theremoveDuplicates function:

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const array = [1, 2, 2, 3, 4, 4, 5];
const uniqueArray = removeDuplicates(array);
console.log(uniqueArray); // Output: [1, 2, 3, 4, 5]

In this example, thearray contains duplicate values. TheremoveDuplicates function is called with thearray as an argument. It returns a new array (uniqueArray) with duplicate values removed. The resultinguniqueArray contains only unique values. Choose the method that suits your needs based on factors such as simplicity, performance, or compatibility requirements.

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