_JavaScript_Reverse_Array

_NodeJS_Reverse_Array.md

JS Reverse Array

let arr1 = Array.from({length: 10000000}, (_, i) => i);

Node version 15.8

• reverse method 274ms
• index swap 9ms
• index swap es6 8ms

reverse_array.js

let arr1 = Array.from({length: 10000000}, (_, i) => i);
console.log(arr1);

console.time('reverse');
arr1.reverse() // 274
console.timeEnd('reverse');
console.log(arr1);

reverse_swap_index.js

function rswap(arr) {
    let [l, r] = [null, null];
    let len = arr.length;
    for (l=0, r=len-1; l < r; l +=1, r -=1) {
        let temp = arr[l];
        arr[l] = arr[r];
        arr[r] = temp;
    }
    return arr;
}

let arr2 = Array.from({length: 10000000}, (_, i) => i);
console.log(arr2);

console.time('temporary swap');
rswap(arr2) // 9ms
console.timeEnd('temporary swap');
console.log(arr2);

reverse_swap_index_es6.js

function rswap2(arr) {
    let [l, r] = [null, null];
    let len = arr.length;
    for (l=0, r=len-1; l < r; l +=1, r -=1) {
        [arr[l], arr[r]] = [arr[r], arr[l]]
    }
    return arr;
}

let arr3 = Array.from({length: 10000000}, (_, i) => i);
console.log(arr3);

console.time('temporary swap2');
rswap(arr3) // 8ms
console.timeEnd('temporary swap2');
console.log(arr3);