For this exercise, write two functions, reverseArray and reverseArrayInPlace. The first, reverseArray, takes an array as argument and produces a new array that has the same elements in the inverse order. The second, reverseArrayInPlace, does what the reverse method does: it modifies the array given as argument in order to reverse its elements. N…

reversearray.js

function reverseArray( arrayToInvert ) {
  // create a variable for the new array
  var invertedArray = [];
  
  // count how many things are in the original array
  numLoops = arrayToInvert.length;
  
  // loop that many times backwards and put each element into the new array
  for ( i = numLoops -1; i >= 0; i-- ) {
  	invertedArray.push( arrayToInvert[i]);
  }
  
  // return the inverted array
  return invertedArray;
 
}

function reverseArrayInPlace( arrayToInvert ) {
  
  // calculate the length of the array
  invertArrayLength = arrayToInvert.length;
  
  // calculate half the length of the array
  numLoops = Math.floor( invertArrayLength / 2 );
 
  // loop that many times and swap the first and last elements
  for ( i = 0; i < numLoops; i++ ) {    
    // hold on to the current number
    var holdNum = arrayToInvert[i];
    
    // get the position of the swap number
    var swapPos = invertArrayLength - 1 - i;
    
    // replace the current number with the swap number
    arrayToInvert[i] = arrayToInvert[swapPos];
    
    // put the hold number into the swap number
    arrayToInvert[swapPos] = holdNum;
  }
  
  // return the inverted array
  return arrayToInvert;
}

console.log(reverseArray(["A", "B", "C"]));
// → ["C", "B", "A"];
var arrayValue = [1, 2, 3, 4, 5];
reverseArrayInPlace(arrayValue);
console.log(arrayValue);
// → [5, 4, 3, 2, 1]