Reverse array in Javascript without mutating original array
Try this recursive solution:
const reverse = ([head, ...tail]) =>
tail.length === 0
? [head] // Base case -- cannot reverse a single element.
: [...reverse(tail), head] // Recursive case
reverse([1]); // [1]
reverse([1,2,3]); // [3,2,1]
reverse('hello').join(''); // 'olleh' -- Strings too!
You can use slice() to make a copy then reverse() it
var newarray = array.slice().reverse();
var array = ['a', 'b', 'c', 'd', 'e'];
var newarray = array.slice().reverse();
console.log('a', array);
console.log('na', newarray);
In ES6:
const newArray = [...array].reverse()
Another ES6 variant:
We can also use .reduceRight()
to create a reversed array without actually reversing it.
let A = ['a', 'b', 'c', 'd', 'e', 'f'];
let B = A.reduceRight((a, c) => (a.push(c), a), []);
console.log(B);
Useful Resources:
Array.prototype.reduceRight()
Arrow Functions
Comma Operator