What are the differences between JavaScript's Array.reduce() and Array.filter() methods when transforming arrays?
Benjamin C

TheArray.reduce() andArray.filter() methods in JavaScript are both used to transform arrays, but they serve different purposes. 1. Array.reduce(): Thereduce() method is used to reduce an array into a single value by executing a reducer function on each element of the array. The reducer function takes four arguments: an accumulator, the current value, the current index, and the array itself. The accumulator is an intermediate value that accumulates the result of the reducer function across iterations. Thereduce() method is useful when you need to perform calculations or aggregations on an array, such as summing up values, calculating averages, or finding the maximum/minimum value. Example usage ofArray.reduce():

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const numbers = [1, 2, 3, 4, 5];

const sum = numbers.reduce((accumulator, currentValue) => accumulator + currentValue, 0);
console.log(sum); // Output: 15

In this example, thereduce() method is used to calculate the sum of all numbers in the array. The accumulator starts with an initial value of 0 and is incremented with each iteration by adding the current value to it. 2. Array.filter(): Thefilter() method, on the other hand, is used to create a new array containing only the elements that satisfy a given condition. It takes a predicate function as an argument, which tests each element of the array and returnstrue orfalse based on the condition. Thefilter() method is useful when you need to extract specific elements from an array based on certain criteria. Example usage ofArray.filter():

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const numbers = [1, 2, 3, 4, 5];

const evenNumbers = numbers.filter((value) => value % 2 === 0);
console.log(evenNumbers); // Output: [2, 4]

In this example, thefilter() method is used to create a new array containing only the even numbers from the original array. The predicate function checks if each element is divisible by 2 and returnstrue for even numbers. To summarize, the main differences betweenArray.reduce() andArray.filter() are: -reduce() reduces an array to a single value, whilefilter() creates a new array with elements that pass a given condition. -reduce() requires a reducer function that accumulates a value, whilefilter() requires a predicate function that tests each element. -reduce() is suitable for performing calculations or aggregations, whilefilter() is useful for extracting specific elements from an array based on a condition. Both methods are powerful and provide flexibility in transforming arrays based on different requirements.

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