Find all Permutations in JavaScript

Generate all permutations of string and filter unique string by using JavaScript

An example of permutations of string would be this:

So we’ve figured out what a permutation is, and established that (depending on the length of the string) we may be looking for a lot of them.

Below is the function to generate permutations:

const findPermutation = (num) => {
  const results = []
  const num_data = num.split('')
  function permute(arr, mem) {
    let cur
    const tmp = mem || []

    for (var i = 0; i < arr.length; i++) {
      cur = arr.splice(i, 1)
      if (arr.length === 0) {
        results.push(tmp.concat(cur))
      }
      permute(arr.slice(), tmp.concat(cur))
      arr.splice(i, 0, cur[0])
    }

    return results
  }
  return permute(num_data)
    .map((t) => t.join(''))
    .filter((value, index, self) => self.indexOf(value) === index)
}

Example:

findPermutation('123');
[ '123', '132', '213', '231', '312', '321' ]

findPermutation('abcd');
[
  'abcd', 'abdc', 'acbd',
  'acdb', 'adbc', 'adcb',
  'bacd', 'badc', 'bcad',
  'bcda', 'bdac', 'bdca',
  'cabd', 'cadb', 'cbad',
  'cbda', 'cdab', 'cdba',
  'dabc', 'dacb', 'dbac',
  'dbca', 'dcab', 'dcba'
]

findPermutation('aabc');
[
  'aabc', 'aacb',
  'abac', 'abca',
  'acab', 'acba',
  'baac', 'baca',
  'bcaa', 'caab',
  'caba', 'cbaa'
]

Hope this article can help you.