Hello fellow developers!
Have you ever wondered about the various ways to use the array.map() function to achieve different transformations?
I have compiled a list of ideas on how to utilize them effectively map() function.
1. Basic Transformation
Transform each element in an array.
const numbers = [1, 2, 3];
const squares = numbers.map(x => x * x);
console.log(squares); // [1, 4, 9]
2. Mapping to Objects
Transform an array of values to an array of objects.
const names = ['Alice', 'Bob', 'Charlie'];
const people = names.map(name => ({ name }));
console.log(people); // [{ name: 'Alice' }, { name: 'Bob' }, { name: 'Charlie' }]
3. Extracting Properties
Extract a specific property from an array of objects.
const users = [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' }
];
const ids = users.map(user => user.id);
console.log(ids); // [1, 2]
4. Changing Array of Arrays
Transform an array of arrays.
const pairs = [[1, 2], [3, 4], [5, 6]];
const summedPairs = pairs.map(pair => pair[0] + pair[1]);
console.log(summedPairs); // [3, 7, 11]
5. Asynchronous Operations
Handle asynchronous operations within map (commonly using Promise.all).
const fetchData = async id => {
// Simulate an async operation
return new Promise(resolve => setTimeout(() => resolve(`Data for ID ${id}`), 1000));
};
const ids = [1, 2, 3];
const promises = ids.map(id => fetchData(id));
Promise.all(promises).then(data => console.log(data)); // ["Data for ID 1", "Data for ID 2", "Data for ID 3"]
6. Conditional Mapping
Apply a transformation conditionally.
const numbers = [1, 2, 3, 4, 5];
const evensDoubled = numbers.map(num => num % 2 === 0 ? num * 2 : num);
console.log(evensDoubled); // [1, 4, 3, 8, 5]
7. Spreading Arrays into Function Arguments
You can use map to spread array elements as arguments to a function.
const numbers = [[1, 2], [3, 4], [5, 6]];
// Creating an array of sums
const sums = numbers.map(([a, b]) => a + b);
console.log(sums); // [3, 7, 11]
8. Zipping Arrays
Combine two arrays into an array of pairs.
const keys = ['name', 'age'];
const values = ['Alice', 25];
const zipped = keys.map((key, i) => [key, values[i]]);
console.log(zipped); // [["name", "Alice"], ["age", 25]]
9. Mapping with Index
Utilizing the index parameter in JavaScript’s map function allows you to include the position of each element in your transformations.
const colors = ['red', 'green', 'blue'];
const colorDescriptions = colors.map((color, index) => `Color ${index + 1}: ${color}`);
console.log(colorDescriptions); // ['Color 1: red', 'Color 2: green', 'Color 3: blue']
10. Flattening an Array
Using map to flatten a 2D array, though flatMap is better suited for this task.
const nestedArray = [[1, 2], [3, 4], [5, 6]];
const flattenedArray = nestedArray.map(subArray => subArray).flat();
console.log(flattenedArray); // [1, 2, 3, 4, 5, 6]
Thank you for reading! Feel free to connect with me on LinkedIn or GitHub.
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