[1,2,3,4,5,6,7,8,9].shuffle() - CSS-Tricks

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July 20, 2013 at 1:27 pm #46565
Kuzyo
Participant
I’m already broken my head with this exercise:

Make this code work:
```
[1,2,3,4,5,6,7,8,9].shuffle() 
// [2, 4, 1, 8, 9, 6, 5, 3, 7] 
```
Can somebody help? It seems I have to use prototype an maybe Math.randam(). Thanks
July 20, 2013 at 4:10 pm #143795

Kuzyo
Participant

It’s from Object-oriented Javascript by Stoyan Stefanov, great book.

July 20, 2013 at 4:33 pm #143797
Kuzyo
Participant
before sleep was that
```
Array.prototype.shuffle = function() { 
  var len = this.length; 
  for ( var i = 0; i < len; i++ ) { 
    var ele = this*, pos = this[Math.floor(Math.random()*len)]; 
    if(pos == undefined) { 
      pos = ele; 
    } 
  } 
  return this; 
};
```
July 21, 2013 at 4:00 am #143833

Kuzyo
Participant

Give me, please some tips, here my result (don’t want to look at Stock overflow, I know there is answer, want to properly uderstand):

Array.prototype.shuffle = function() {
var len = this.length,
shuffleArr = [];

for ( var i = 0; i < len; i++ ) {
var elem = this,
pos = Math.floor( Math.random() * len );

if ( shuffleArr[pos] == undefined) {
shuffleArr[pos] = elem
shuffleArr.push(elem);
}

}

return shuffleArr;
}

var a =[1,2,3,4,5,6,7,8,9];

a.shuffle()

July 21, 2013 at 7:30 am #143864

Kuzyo
Participant

It’s nice solution **shuffleArr.splice(pos, 0, elem);** I didn’t know how to make that elem go to different position, because Math.random() can repeat themselves, thats why there was this strange

if ( shuffleArr[pos] == undefined)

but, why you use:

pos = Math.floor( Math.random() * (shuffleArr.length + 1) )

this works too:

pos = Math.floor( Math.random() * len );

Thanks @CrocoDillon for your help
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