Syntax error Take an array of integers and create an array of all the possible permutations in JavaScript

Take an array of integers and create an array of all the possible permutations in JavaScript

We are required to write a function that does the following −

  • takes an array of integers as an argument (e.g. [1,2,3,4])

  • creates an array of all the possible permutations of [1,2,3,4], with each permutation having a length of 4 (i.e., the length of original array)

Example

The code for this will be −

const arr = [1, 2, 3, 4];
const permute = (arr = [], res = [], used = []) => {
   let i, ch;
   for (i = 0; i < arr.length; i++) {
      ch = arr.splice(i, 1)[0];
      used.push(ch);
      if (arr.length === 0) {
         res.push(used.slice());
      }
      permute(arr, res, used);
      arr.splice(i, 0, ch);
      used.pop();
   };
   return res;
};
console.log(permute(arr));

Output

And the output in the console will be −

[
   [ 1, 2, 3, 4 ], [ 1, 2, 4, 3 ],
   [ 1, 3, 2, 4 ], [ 1, 3, 4, 2 ],
   [ 1, 4, 2, 3 ], [ 1, 4, 3, 2 ],
   [ 2, 1, 3, 4 ], [ 2, 1, 4, 3 ],
   [ 2, 3, 1, 4 ], [ 2, 3, 4, 1 ],
   [ 2, 4, 1, 3 ], [ 2, 4, 3, 1 ],
   [ 3, 1, 2, 4 ], [ 3, 1, 4, 2 ],
   [ 3, 2, 1, 4 ], [ 3, 2, 4, 1 ],
   [ 3, 4, 1, 2 ], [ 3, 4, 2, 1 ],
   [ 4, 1, 2, 3 ], [ 4, 1, 3, 2 ],
   [ 4, 2, 1, 3 ], [ 4, 2, 3, 1 ],
   [ 4, 3, 1, 2 ], [ 4, 3, 2, 1 ]
]
Updated on: 2020-11-21T09:24:10+05:30

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