Data MasteryMonday, January 26, 2026

Modern Array Methods

Map, Filter, and Reduce explained.

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Stop writing for loops. Modern JS relies on functional programming methods: Map, Filter, and Reduce.

The Pipeline (Chaining)

Clean Code Power Move

You can attach methods together like Lego bricks. The output of one becomes the input of the next.

const products = [
  { name: "Laptop", price: 1000, inStock: true },
  { name: "Phone", price: 500, inStock: false },
  { name: "Tablet", price: 300, inStock: true }
];

// Goal: Get total value of available items
const totalValue = products
  .filter(item => item.inStock)       // 1. Remove out of stock
  .map(item => item.price)            // 2. Extract just prices
  .reduce((acc, price) => acc + price, 0); // 3. Sum them up

console.log(totalValue); // 1300 (1000 + 300)

Map vs ForEach

Use map when you want to create a new array. Use forEach when you just want to do something (like log to console) and return nothing.

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