js slice in place code example

Example 1: javascript slice array

// array.slice(start, end)
const FRUITS = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
var citrus = FRUITS.slice(1, 3);
// citrus => [ 'Orange', 'Lemon' ]

// Negative values slice in the opposite direction
var fromTheEnd = FRUITS.slice(-3, -1);
// fromTheEnd => [ 'Lemon', 'Apple' ]

Example 2: use of slice and splice add elements array

function frankenSplice(arr1, arr2, n) {
  // Create a copy of arr2.
  let combinedArrays = arr2.slice()
  //                   [4, 5, 6]

  // Insert all the elements of arr1 into arr2 beginning
  // at the index specified by n. We're using the spread
  // operator "..." to insert each individual element of 
  // arr1 instead of the whole array.
  combinedArrays.splice(n, 0, ...arr1)
  //                   (1, 0, ...[1, 2, 3])
  //                   [4, 1, 2, 3, 5, 6]

  // Return the combined arrays.
  return combinedArrays
}

frankenSplice([1, 2, 3], [4, 5, 6], 1);