有人可以解释一下这个功能是如何工作的吗？

Question

function shuffle(o) {
    for(var j, x, i = o.length; i; j = parseInt(Math.random() * i), x = o[--i], o[i] = 
    o[j], o[j] = x);
    return o;
};

Not quite sure what the last part is doing

Answer 1

This looks like someone taking up the challenge of "I can do this in one line" , which is a very neat and fun challenge, but has no place in real world code - your coworkers will hate you. So let's expand it into something readable:

function shuffle(o) {
    // iterate over the entire input array "o"
    for(var i = o.length - 1; i; i--) {
      // get the "current" item and save it in variable "x"
      var x = o[i];
      // generate a random number within the bounds of the array
      var j = parseInt(Math.random() * (i + 1));

      // The next two lines essentially swap item[i] and item[j]
      // set the "current" item to a randomly picked item
      o[i] = o[j];
      // put the "current" item in the random position
      o[j] = x;
    }

    return o;
};

Answer 2

function shuffle(inputArray) { let i = inputArray.length; while (i) { const j = parseInt(Math.random() * i); // generate random integer smaller than i (Math.random() generates random number between 0 and 1) i = i-1; // swap elements on position i and j const element = inputArray[i]; inputArray[i] = inputArray[j] inputArray[j] = x; } return inputArray; };