function stringPermutations(str) {

let letters = str.split('')

, results = [[letters.shift()]]

while (letters.length) {

const currLetter = letters.shift()

let tmpResults = []

results.forEach(result => {

let rIdx = 0

while (rIdx <= result.length) {

const tmp = [...result]

tmp.splice(rIdx, 0, currLetter)

tmpResults.push(tmp)

rIdx++

}

})

results = tmpResults

}

return results

.map(letterArray => letterArray.join(''))

.filter((el, idx, self) => (self.indexOf(el) === idx))

.sort()

}