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JavaScript - reverse array
4
points
In this article we would like to show how to reverse array in JavaScript.
Quick solution:
// ONLINE-RUNNER:browser;
var array = ['a', 'b', 'c'];
var reversedArray = array.reverse();
function print(array) {
console.log(array.join(' '));
}
print(array); // c b a <------ Pay attention or use copy !!!
print(reversedArray); // c b a
Note: be careful reversing array because
reverse()
method works on source array obcject. It is safe to callarray.slice().reverse()
.
Safe reversion example
When we use array in other place of application it is safe to use sourse array copy.
// ONLINE-RUNNER:browser;
var array = ['a', 'b', 'c'];
var reversedArray = array.slice().reverse();
function print(array) {
console.log(array.join(' '));
}
print(array); // a b c
print(reversedArray); // c b a
Array
map()
method example
In 2009, ES5 intoduced Array.prototype.map()
method that let us to write quick reversion logic with arrow function.
// ONLINE-RUNNER:browser;
var array = ['a', 'b', 'c'];
var reversedArray = array.map((item, index, array) => array[array.length - 1 - index]);
function print(array) {
console.log(array.join(' '));
}
print(array); // a b c
print(reversedArray); // c b a