Randomly display group

[kopi3310]

Currently I'm working on a project like flappy bird using Phaser. The pipe is replace with several combination of picture, as picture here .

 

I use Math.random to display the moving object every 2 second but its not proper. Below is my code for example. If I have 10 set of object then I need to create 10 statement:

 

    ...

    add_red_ribbon: function(x, y) {

        var add_red_ribbon= this.red_ribbon.getFirstDead();

        add_red_ribbon.reset(x, y);

        add_red_ribbon.body.velocity.x = -200; 

        add_red_ribbon.outOfBoundsKill = true;

    },

    add_small_flag: function(x, y) {

        var add_small_flag= this.small_flag.getFirstDead();

        add_small_flag.reset(x, y);

        add_small_flag.body.velocity.x = -200; 

        add_small_flag.outOfBoundsKill = true;

    },...

 

    var random = Math.floor((Math.random()*2) + 1);

 

if (random == 1){

this.red_ribbon(700, 0); 

this.add_small_flag(700, 430);

}else if(random == 2){

this.yellow_ribbon(700, 0);

this.guy(700, 258);

}...

 

Is there any better way to accomplish this? 

 

One more problem is its overlap each time its display, how to fix this. Thank you.