JS challenge question

Question

var x =[2,3,2,5];
for(var i = 0; i<x.length-1; i++) {
x[i]=x[i+1];
}
document.write(x);

Output is 3,2,5,5

Please, help me to understand why we have such output?

If we put document.write(x) inside the cycle we will have the following iterations;
3,3,2,5
3,2,2,5
3,2,5,5

I can not understand why. How does it work?
Thank you for your help.

Answer 1

Step 1: i=0, which is less than the array's length. So the first element becomes 3
Step 2: i=1, which is lessvthan the array's length. So the second element becomes 2
Step 3: i=2, which is less than the array's length. So the third element becomes 5
Step 4: i=3, which is equal to the array's length. So the fourth element remains unchanged.

Answer 2

var x =[2,3,2,5];
var t=x[0];
for(var i = 0; i<x.length-1; i++) {
x[i]=x[i+1];
}
x[x.length-1]=t;
document.write(x);

This will rotate the array giving output of 3,2,5,2

Answer 3

Thank you, guys!

Answer 4

1: var x =[2,3,2,5];
2: for(var i = 0; i<x.length-1; i++) {
3: x[i]=x[i+1];
4: }
Line 1 sets x to 2,3,2,5
Line 2 sets i to 0
Line 3 copies x[0+1] to x[0] replacing 2 with 3 (3,3,2,5)
Line 4 goes back to 2.
Line 2 sets i to 1
Line 3 copies x[1+1] to x[1] replacing 3 with 2 (3,2,2,5)
Line 4 goes back to 2.
Line 2 sets i to 2
Line 3 copies x[2+1] to x[2] replacing 2 with 5 (3,2,5,5)
Line 4 goes back to 2.
Line 2 sets i to 3; it is now = to x.length-1 so goes to Line 5