Javascript Reduce Method Examples

The reduce method in JavaScript is used to reduce the array to a single value and executes a provided function for each value of array and the return value of the function is stored in an accumulator.

Syntax

array.reduce(callback(accumulator, currentValue, currentIndex, array), initialValue);

Use cases of reduce in real scenarios:

1. Calculating Totals

const products = [
  { name: "Cactus", price: 30 },
  { name: "Pot", price: 20 },
  { name: "Glass", price: 10 }
];

const totalPriceReduce = products.reduce((sum, product) => sum + product.price, 0);

console.log("Total price:", totalPriceReduce); // Output: Total price: 60

2. Finding Maximum Value

const prices = [30, 20, 10];

const maxPriceReduce = prices.reduce((max, price) =&gt; Math.max(max, price), -Infinity);

console.log("Max price:", maxPriceReduce); // Output: Max price: 30

3. Removing Duplicates

const prices = [30, 20, 10, 20]

let newPrices = prices.reduce(function (accumulator, curValue) {
 if(accumulator.indexOf(curValue) === -1) {
 accumulator.push(curValue)
 }
 return accumulator
}, [])

console.log(newPrices); // Output: 30, 20, 10