Javascript array reverse function unexpected behavior

Question

I would like to understand why situation 1 and situation 2 don\'t return the same results.

Situation 1 :

var array1 = [\"1\", \"2\", \"3\"];
var arra         


        

Answer 1

The reverse method transposes the elements of the calling array object in place, mutating the array, and returning a reference to the array. Thus, it does not return the reversed array.

CHECK the manuel. https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/reverse

Answer 2

It's important to note that Array.reverse() does two things:

• It mutates the array it's given by reversing it
• It returns a reference to the array that was just reversed

Let's take a look at your examples and what's going on/

Situation One

var array1 = ["1", "2", "3"];  // Creates new array
var array2 = array1.reverse(); // Reverse array1 and stores reference to array1 in array2

// Since array1 and array2 point to the same object, they will have
// the same values since they are pointing to the same object
console.log(array1); // ["3", "2", "1"]
console.log(array2); // ["3", "2", "1"]

Situation Two

var array1 = ["1", "2", "3"];  // Creates new array
var array2 = array1;           // array2 now holds a reference to array1

// Same as the previous example, array1 and array2 both have the
// same values since they are pointing to the same object    
console.log(array1);           // ["1", "2", "3"]

// Now we reverse array2, which reverses array1 AND array2
console.log(array2.reverse()); // ["3", "2", "1"]

// array1 is now also reversed
console.log(array1);           // ["3", "2", "1"]

In the second situation, after you call array2.reverse(), both array1 and array2 become reversed since they're pointing to the same object reference.