Javascript Filter Vs Reduce

Javascript filter vs reduce

Created By: chatGPT

In JavaScript, both filter and reduce are higher-order functions that operate on arrays, allowing for functional programming patterns. However, they serve different purposes. filter creates a new array with all elements that pass a test implemented by the provided function, while reduce applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.To illustrate the difference, here’s how you might use each method to manipulate an array of numbers.

Using filter to get even numbers from an array:

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const evenNumbers = numbers.filter(num => num % 2 === 0);
console.log(evenNumbers); // Output: [2, 4, 6, 8, 10]

In this example, filter takes a function that checks if a number is even and creates a new array containing only those numbers.

Now let’s see how reduce can be used to calculate the sum of all numbers in the array:

const sum = numbers.reduce((accumulator, currentValue) => {
    return accumulator + currentValue;
}, 0);

console.log(sum); // Output: 55

Here, reduce is used to accumulate the sum of all numbers in the numbers array. The accumulator starts at 0, and for each number in the array, it adds that number to the accumulator.In summary, use filter when you want to create a new array with a subset of the elements based on a certain condition and use reduce when you need to aggregate the values in an array into a single result.