我有一个这样的数组:

var arr1 = ["a", "b", "c", "d"];

我如何随机化/打乱它?


当前回答

或者像上面所有的答案,但简而言之。

function shuffle(a) { for (var c, d, b = a.length; 0 !== b;)d = Math.floor(Math.random() * b), b -= 1, c = a[b], a[b] = a[d], a[d] = c; return a }

其他回答

随机化数组,无重复项

    function randomize(array){
        let nums = [];
        for(let i = 0; i < array.length; ++i){
            nums.push(i);
        }   
        nums.sort(() => Math.random() - Math.random()).slice(0, array.length)
        for(let i = 0; i < array.length; ++i){
            array[i] = array[nums[i]];
        }
    }
    randomize(array);

对CoolAJ86答案的简单修改,不修改原始数组:

 /**
 * Returns a new array whose contents are a shuffled copy of the original array.
 * @param {Array} The items to shuffle.
 * https://stackoverflow.com/a/2450976/1673761
 * https://stackoverflow.com/a/44071316/1673761
 */
const shuffle = (array) => {
  let currentIndex = array.length;
  let temporaryValue;
  let randomIndex;
  const newArray = array.slice();
  // While there remains elements to shuffle...
  while (currentIndex) {
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;
    // Swap it with the current element.
    temporaryValue = newArray[currentIndex];
    newArray[currentIndex] = newArray[randomIndex];
    newArray[randomIndex] = temporaryValue;
  }
  return newArray;
};
var shuffle = function(array) {
   temp = [];
   originalLength = array.length;
   for (var i = 0; i < originalLength; i++) {
     temp.push(array.splice(Math.floor(Math.random()*array.length),1));
   }
   return temp;
};

可以(但不应该)将其用作Array中的原型:

来自ChristopheD:

Array.prototype.shuffle = function() {
  var i = this.length, j, temp;
  if ( i == 0 ) return this;
  while ( --i ) {
     j = Math.floor( Math.random() * ( i + 1 ) );
     temp = this[i];
     this[i] = this[j];
     this[j] = temp;
  }
  return this;
}

费希尔·耶茨在javascript中洗牌。我在这里发表这篇文章是因为与这里的其他答案相比,使用两个实用函数(swap和randInt)澄清了算法。

function swap(arr, i, j) { 
  // swaps two elements of an array in place
  var temp = arr[i];
  arr[i] = arr[j];
  arr[j] = temp;
}
function randInt(max) { 
  // returns random integer between 0 and max-1 inclusive.
  return Math.floor(Math.random()*max);
}
function shuffle(arr) {
  // For each slot in the array (starting at the end), 
  // pick an element randomly from the unplaced elements and
  // place it in the slot, exchanging places with the 
  // element in the slot. 
  for(var slot = arr.length - 1; slot > 0; slot--){
    var element = randInt(slot+1);
    swap(arr, element, slot);
  }
}