generate random number array javascript from principal array

1let numbers = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20],
2    generated = [];
3for (let i = 0; i < 10; i++)
4{
5    let random_index;
6    while(!random_index)
7    {
8        let tmp = Math.floor(Math.random() * numbers.length);        
9        if( !generated.filter( (g) => numbers[tmp] == g).length )
10            random_index = tmp;
11    }
12    generated.push(numbers[random_index]);
13}
14console.log(generated);

1//This example is to generate an array with 40 random elements, with random values from 0 to 39 
2
3for (var a=[],i=0;i<40;++i) a[i]=i;
4
5// http://stackoverflow.com/questions/962802#962890
6function shuffle(array) {
7  var tmp, current, top = array.length;
8  if(top) while(--top) {
9    current = Math.floor(Math.random() * (top + 1));
10    tmp = array[current];
11    array[current] = array[top];
12    array[top] = tmp;
13  }
14  return array;
15}
16
17a = shuffle(a);
18