How to display 20 random symbols from pool of 50?

Question

Hi,
I have a project that plays a random symbol when a button is clicked, however I want a random symbol to be shown each time the button is pressed for 20 times.
How do I limit the display to just show 20 random symbols from a pool of 50?
This is the code I am using on the button that displays a random symbol each time clicked:
// RADOMIZE
          var myVar = Math.floor((Math.random()*4)+1);
// create symbol into container
          var container = sym.$('container');
          var myAni = sym.createChildSymbol("Symbol_" + myVar, container);
          myAni.getSymbolElement().css({
          'position': 'absolute',
          'left': 0,
          'top': 0,
Thanks

Answer 1

You need to shuffle the array and then randomize the 20 elements".
Here is a example showing you how to do with 4 elements:
var originalArray=['one','two','three','four','five','six','seven','eight','nine','ten'];
// shuffle the original array
originalArray.sort(function() {return 0.5 - Math.random()});
// then  limit the array to the 4 first elements
originalArray.length =4;
// the alert is to show that you have 4 elements and what they are - added 5 to show element 5 does not exist.
alert(originalArray[0] + ' ' +originalArray[1] + ' ' +originalArray[2] + ' ' +originalArray[3] + ' ' +originalArray[4]);
// randomize the elements in the new array
var myVar = Math.floor((Math.random()*3)+1);
sym.$('Text').click(function(){
          // myVar++;
     // shows one of the 4 numbers
          sym.$('Text').html(originalArray[myVar]);