Write a function that accepts an integer N and returns a NxN spiral matrix.

spiral_matrix.js

// matrix(3);
//     [[1, 2, 3],
//      [8, 9, 4],
//      [7, 6, 5]]
 
// matrix(4);
//     [[1,   2,  3, 4],
//      [12, 13, 14, 5],
//      [11, 16, 15, 6],
//      [10,  9,  8, 7]]

function matrix(n) {
	const results = [];
	
	for (let i = 0; i < n; i++) {
		results.push([]);
	}
	
	let counter = 1;
	let startColumn = 0;
	let endColumn = n - 1;
	let startRow = 0;
	let endRow = n - 1;
	
	while (startColumn <= endColumn && startRow <= endRow) {
		// Top Row
		for (let i = startColumn; i <= endColumn; i++) {
			results[startRow][i] = counter;
			counter++
		}
		startRow++;
		
		// Right Column
		for (let i = startRow; i <= endRow; i++) {
			results[i][endColumn] = counter;
			counter++;
		}
		endColumn--;
		
		// Bottom Row
		for (let i = endColumn; i >= startColumn; i--) {
			results[endRow][i] = counter;
			counter++;
		}
		endRow--;
		
		// Start Column
		for (let i = endRow; i >= startRow; i--) {
			results[i][startColumn] = counter;
			counter++;
		}
		startColumn++;
	}
	
	return results;
}