Two ways for JavaScript to randomly extract different elements from an array _javascript techniques

Source: Internet
Author: User
Tags shuffle

First, the general algorithm

The first method is more conventional, the test has a bug, the amount of data returned randomly several times after the object directly is a function rather than object. Of course, simple data types should not have this problem.

Sample code

/**
     randomly extracts data from the array 2016-09-09
   **/
   function Getarritem (arr, num) {
     var temp_array = new Array ();
     For (var index in arr) {
       temp_array.push (Arr[index]);
     }
     var return_array = new Array ();
     for (var i = 0; i < num i++) {
       if (Temp_array.length > 0) {
         var arrindex = Math.floor (Math.random () * tem P_array.length);
         Return_array[i] = Temp_array[arrindex];
         Temp_array.splice (Arrindex, 1);
       } else {break
         ;
       }
     }
     return return_array;
   }

Second, shuffle algorithm

The second is to use the shuffle algorithm, the pro-test effective.

Sample code

/**
      Randomized original array
    **/
    function Shuffle (array) {
      var m = array.length,
        t, I;
      If there are elements
      left ... while (m) {
        //randomly Select an element ...
        i = Math.floor (Math.random () * m--);
        Exchange with the current element
        t = array[m];
        ARRAY[M] = Array[i];
        Array[i] = t;
      }
      return array;
    }
 
Use
var message = Shuffle (Totalarr);
message = Message.slice (0, 3);

The above is for you to sum up the two kinds of JavaScript from the array random out of different elements of the method, I hope this article can be a study or work to bring some help, if you have questions you can message exchange.

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