How to iterate over all possible combinations of digits in a number?

Question

JavaScript

There is some number 1234.
Task: find and execute a certain code with all possible variations of the digits in a given number: 1243, 1432, 4231etc.
How to iterate over all possible combinations?

Answer 1

var permArr = [],
  usedChars = [];

function permute(input) {
  var i, ch;
  for (i = 0; i < input.length; i++) {
    ch = input.splice(i, 1)[0];
    usedChars.push(ch);
    if (input.length == 0) {
      permArr.push(usedChars.slice());
    }
    permute(input);
    input.splice(i, 0, ch);
    usedChars.pop();
  }
  return permArr
};

document.write(JSON.stringify(permute([5, 3, 7, 1])));

Not mine, of course. Just get out of here .