Function for generating permutations of a list.

permutations.js

function permutations(list)
{
	// Empty list has one permutation
	if (list.length == 0)
		return [[]];
		
		
	var result = [];
	
	for (var i=0; i<list.length; i++)
	{
		// Clone list (kind of)
		var copy = Object.create(list);

		// Cut one element from list
		var head = copy.splice(i, 1);
		
		// Permute rest of list
		var rest = permutations(copy);
		
		// Add head to each permutation of rest of list
		for (var j=0; j<rest.length; j++)
		{
			var next = head.concat(rest[j]);
			result.push(next);
		}
	}
	
	return result;
}

Here's a TS version

export function permutations<T>(list: T[]): T[][] {
  // Empty list has one permutation
  if (list.length === 0) return [[]];
  const result: T[][] = [];
  for (let i = 0; i < list.length; i++) {
    // Clone list (kind of)
    const copy = Object.create(list);
    // Cut one element from list
    const head = copy.splice(i, 1);
    // Permute rest of list
    const rest = permutations(copy);
    // Add head to each permutation of rest of list
    for (let j = 0; j < rest.length; j++) {
      const next = head.concat(rest[j]);
      result.push(next);
    }
  }
  return result;
}