reverseArrayInPlace.js

/*-----------------------------------------------------------------------------
1.swap the elements
2.temporary variable is useful.

the reference is from UdemyCourse: LearningAlgorithmsInJavascriptFromScratch
-----------------------------------------------------------------------------*/

function reverseArrayInPlace(arr) {
  
  // dsakhpr  d <-> r    s <-> p    a <-> h
  for (var i = 0; i < arr.length / 2 ; i++) {
    // swapping
    var tmp = arr[i];
    arr[i] = arr[arr.length - 1 - i];
    arr[arr.length - 1 - i] = tmp;
  }
  
  return arr;
}

reverseArrayInPlace([1,'421',[41]])
// [ [ 41 ], '421', 1 ]