Recursive implementation of string characters permutation covering all possible cases without duplication

permute-characters.js

/** 
 * Recursive implementation of string characters permutation 
 * covering all possible cases without duplication
 */
function permute(str) {
  var stack = []

  if (str.length === 1) {
    return [ str ]
  }

  for (var i = 0; i < str.length; i += 1) {
    var char = str[i]
    
    var head = str.slice(0, i)
    var tail = str.slice(i+1)
    var buf = permute(head.concat(tail))
    
    for (var x = 0; x < buf.length; x += 1) {
      stack.push(char + buf[x])
    }
  }

  return stack
}

var result = permute('abc')
console.log(JSON.stringify(result, null, 2))