JavaScript provides several powerful array methods to manipulate and iterate over data efficiently. Among them, map(), filter(), reduce(), and forEach() are widely used but serve different purposes. In this guide, we'll explore their differences with examples.
Understanding the Differences
| Method | Purpose | Returns | Mutates Original Array? |
|---|---|---|---|
map() | Transforms each element and creates a new array. | A new array with transformed elements. | No |
filter() | Filters elements based on a condition. | A new array with selected elements. | No |
reduce() | Reduces the array to a single value (e.g., sum, object, etc.). | A single accumulated value. | No |
forEach() | Iterates through elements but does not return a new array. | undefined | No |
1. map() - Transforming Elements
map() is used when you need to apply a function to each element and create a new array.
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2. filter() - Selecting Elements
filter() is used to create a new array containing only elements that meet a certain condition.
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3. reduce() - Accumulating a Single Value
reduce() is used when you need to compute a single value from an array, such as sum, product, or an object.
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4. forEach() - Iterating Without Returning
forEach() is used to execute a function on each element but does not return a new array.
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Conclusion
- Use
map()when you need to transform elements and get a new array. - Use
filter()when you need to select elements based on a condition. - Use
reduce()when you need to accumulate values into a single result. - Use
forEach()when you need to iterate but don't need a new array.
Understanding these methods will help you write cleaner and more efficient JavaScript code. Happy coding! 🚀