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JavaScript Spread and Rest Operators Explained: A Beginner’s Guide to ES6+

#programming #javascript #beginners #webdev

JavaScript keeps getting better with new updates, and ES6+ brings in powerful tools to make coding simpler. The spread operator and the rest operator may look identical with ..., but they work in different ways. Spread helps you expand arrays and objects, while rest lets you collect multiple values into one place. For beginners, learning these will make the code more comprehensible and clearer.

What You’ll Learn

  • The difference between the spread and rest operators.
  • How spread expands arrays and objects.
  • How rest collects multiple values into arrays.
  • Real-world examples to use in projects.

Spread Operator in JavaScript

The spread operator “spreads out” items inside an array or object.

Example with arrays:

const num = [1, 2, 3];
const newNum = [...num, 4, 5];
console.log(newNum); // [1, 2, 3, 4, 5]
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This makes it easy to copy arrays or merge them.

Real-world example:

Imagine you have a shopping cart, and include additional products in it.

const cart = ["apple", "banana"];
const newItems = ["orange", "mango"];
const updatedCart = [...cart, ...newItems];
console.log(updatedCart); // ["apple", "banana", "orange", "mango"]
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The spread operator helps you combine the old cart with new items quickly.

Rest Operator in JavaScript

The rest operator works the other way. It takes multiple values and groups them into an array.

Example with functions:

function sum(...numbers) {
  return numbers.reduce((total, num) => total + num, 0);
}
console.log(sum(1, 2, 3, 4)); // 10
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In this example, rest combines all the numbers into an array, which makes summing them simple.

Real-world example:

Imagine you’re building a game that needs to keep track of scores.

function logScores(player, ...scores) {
  console.log(`${player}'s scores:`, scores);
}
logScores("Wisdom", 10, 20, 30, 40);
// Wisdom's scores: [10, 20, 30, 40]
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The rest operator collects all the scores into one array, making it easier to work with.

How Spread and Rest Work Together

Even though spread and rest use the same three dots (...), they work in opposite ways. Spread expands items, while rest collects them. Together, they make handling arrays, objects, and function arguments are more versatile and powerful.

Key Takeaways

  • Spread (...) takes an array or object and breaks it into individual items.
  • Rest (...) collects several values and puts them into one array.
  • Spread is useful for copying and merging data.
  • Rest is useful for handling multiple function arguments.
  • Both operators improve the readability and structure of your JavaScript code.

Conclusion

The spread and rest operators are simple yet powerful features in JavaScript. Spread helps you copy or merge data, while rest lets you gather multiple values into one variable. With real-world uses like adding items to a shopping cart or collecting game scores, these tools can make your code cleaner, faster, and easier to maintain.

By practicing them often, you’ll get more comfortable writing modern JavaScript that looks professional and is easy to understand.

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