在此插入代码

var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]; alert(arr.filter(function(x){

for(var i = 2;i<=x/2;i++){
    if(x % i === 0)
        break;
}
if(i<=x/2)
    return false;
else
    return true;

}));