how to rotate a given matrix by one element clockwise in JavaScript

Valiant Lupori Buzzactaxe :

Ok so I came up with this code I would like to implement in JS but I am not very advanced in JS and I am having trouble printing it out or even testing it...could anyone check the code and help me console.log it?

this is my goal:

┌     ┐    ┌     ┐ 
|1 2 3|    |4 1 2| 
|4 5 6| -> |7 5 3| 
|7 8 9|    |8 9 6|   
└     ┘    └     ┘

This is the code I wrote:

var matrix = [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ];

function rotateMatrix(matrix) {
    //boundery indication for row and column (index)
    let maxRow = matrix.length - 1;
    let maxCol = matrix.length - 1;
    let row = 0;
    let col = 0;

    //keeps track of ring which we are working with
    while (row < maxRow && col < maxCol) {
        // initial temp starting with 4 being the numb. moving clockwise
        let previous = matrix[row + 1][col];

        //loop through TOP ROW (row 0 ) moving 1 spot
        for (let i = col; i <= maxCol; i++) {
            let current = matrix[row][i]; //current makes space for previous starting w/1
            matrix[row][i] = previous; // putting final num in new spot starting w/4 putting in slot 1
            previous = current;//leaving the loop with previous = 3
        }
        row++; //moves to row index 1

        //starting in row index 1 loop through RIGHT most COLUMN (col 2) moving 1 spot down
        for (let j = row; j <= maxRow; j++) {
            let current = matrix[j][maxCol]; //current makes space for previous starting w/6
            matrix[j][maxCol] = previous; //starting with 3 moving in slot 6
            previous = current; //leaving the loop with previous = 9
        }
        maxCol--; // moves to column index 1
        //loop through the BOTTOM ROW (row 2) moving 1 spot left
        if(row < maxRow + 1){
            for(let i = maxCol; i >= col; i--){
                let current = matrix[maxRow][i];
                matrix[maxRow][i] = previous;
                previous = current;
            }
            maxRow--;
        }
        //loop through the LEFT COLUMN (col 0) moving 1 spot up
        if (col < maxCol - 1) {
            for (let i = maxCol; i<= row; i--) {
                let current = matrix[i][col];
                matrix[i][col] = previous;
                previous = current;             
            }
            col++;
        }
    }
}

tevemadar :

For rotating clockwise, you have to go around counter-clockwise. Also, the element you store at the beginning will be needed at the end, and it is not needed anywhere else.

function p(m){
  for(let l of m)
    console.log(l.join());
  console.log('---');
}
function ccwrectangle(mtx,top,left,bottom,right){
  let elem=mtx[top][left];
  for(let y=top;y<bottom;y++)           // downwards on the left
    mtx[y][left]=mtx[y+1][left];
  for(let x=left;x<right;x++)           // righwards at the bottom
    mtx[bottom][x]=mtx[bottom][x+1];
  for(let y=bottom;y>top;y--)           // upwards on the right
    mtx[y][right]=mtx[y-1][right];
  for(let x=right;x>left+1;x--)         // leftwards on the top
    mtx[top][x]=mtx[top][x-1];
  mtx[top][left+1]=elem;
}

let m1=[[1,2,3],[4,5,6],[7,8,9]];
p(m1);
ccwrectangle(m1,0,0,2,2);
p(m1);

let m2=[[1,2,3,4],[5,6,7,8],[9,'A','B','C'],['D','E','F','0']];
p(m2);
ccwrectangle(m2,0,0,3,3);
ccwrectangle(m2,1,1,2,2);
p(m2);

ccwrectangle() rotates one "ring" at a time, so for matrices with multiple rings it runs multiple times. The general way for square matrices would be something like

for(let a=0,b=mtx.length-1;b>a;a++,b--)
  ccwrectangle(mtx,a,a,b,b);

(Also for rectangular ones after all, just in that case left-right and top-bottom pairs have to be tracked separately and the loop ends when any one of the pairs meet)