JS Spiral Matrix Iterator

spiral.js

function border(matrix, row, col, len) {
	
	var items=[];
	var endCol = col - 1;	
	var endRow = row;
	
	//top
	for(;col < len; col++) {
		items.push(matrix[row][col]);
	}
	
	//right
	col--;
	row++;	
	for(;row < len; row++) {
		items.push(matrix[row][col]);
	}
	
	//bottom
	col--;
	row--;
	for(;col > endCol; col--) {
		items.push(matrix[row][col]);
	}
	
	//left
	col++;
	row--;
	for(;row > endRow; row--) {
		items.push(matrix[row][col]);
	}
	
	return items;
}

function spiral(matrix) {
	
	var items = [];
	var i=0;
	
	while(items.length < Math.pow(matrix.length, 2)) {
		items = items.concat(border(matrix, i, i, matrix.length-i));		
		i++;
	}
	
	return items;
	
}

/**
 * 0  1  2  3
 * 4  5  6  7
 * 8  9  10 11
 * 12 13 14 15 
 *
 * 0,1,2,3,7,11,15,14,13,12,8,4,5,6,10,9
 */
var matrix4x4 = [[0,1,2,3],[4,5,6,7],[8,9,10,11],[12,13,14,15]]
console.log(border(matrix4x4, 0, 0, matrix4x4.length));
console.log(spiral(matrix4x4));
/**
 * 0 1 2
 * 3 4 5
 * 6 7 8
 *
 * 0,1,2,5,8,7,6,3,4
 */
var matrix3x3 = [[0,1,2],[3,4,5],[6,7,8]]
console.log(border(matrix3x3, 0, 0, matrix3x3.length));
console.log(spiral(matrix3x3));
/**
 * 0 1
 * 2 3
 *
 * 0,1,3,2 
 */
var matrix2x2 = [[0,1],[2,3]]
console.log(border(matrix2x2, 0, 0, matrix2x2.length));
console.log(spiral(matrix2x2));
/**
 * 0
 * 
 * 0
 */
var matrix1x1 = [[0]]
console.log(border(matrix1x1, 0, 0, matrix1x1.length));
console.log(spiral(matrix1x1));