We are required to write a JavaScript function that takes in an array, a start index and an end index. The function should reverse the portion of the array between the start index and end index.
For example −
If the array is −
const arr = [2, 6, 5, 8, 3, 5, 2, 6, 7];
And the start index and end index are 3, 7 respectively, then the array should be reversed to −
const output = [2, 6, 5, 2, 5, 3, 8, 6, 7];
Example
Following is the code −
const arr = [2, 6, 5, 8, 3, 5, 2, 6, 7];
const start = 3, end = 7;
const reverse = arr => {
const { length: l } = arr;
for(let i = 0; i < Math.floor(l/2); i++){
const temp = arr[i];
arr[i] = arr[l-i-1];
arr[l-i-1] = temp;
};
return arr;
};
const reverseBetween = (arr, start, end) => {
const num = Math.min(end - start, arr.length - start);
arr.splice(start, 0, ...reverse(arr.splice(start, num)));
}
reverseBetween(arr, start, end);
console.log(arr);Output
This will produce the following output in console −
[ 2, 6, 5, 2, 5, 3, 8, 6, 7 ]