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Reverse array in Javascript without mutating original array

Array.prototype.reverse reverses the contents of an array in place (with mutation)...

Is there a similarly simple strategy for reversing an array without altering the contents of the original array (without mutation)?

over 4 years ago · Santiago Trujillo
3 answers
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0

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);

over 4 years ago · Santiago Trujillo Report

0

In ES6:

const newArray = [...array].reverse()
over 4 years ago · Santiago Trujillo Report

0

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
over 4 years ago · Santiago Trujillo Report
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