Collision check loop stops looping after enemy is spawned

Question

So I have been making this little shooter game with javascript and I have ran to a problem I cant figure out.

I have a collision check which checks if any alive enemy collides with the player or a bullet using a for loop. The loop runs fine until I spawn an enemy.

In the beginning of the for loop you can see console.log, it logs numbers only ti­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ll the first alive enemy's index. For example if enemies[4] is alive and no other enemies with index before that are alive, it keeps logging 0, 1, 2, 3 and 4. If I then kill all the enemies the loop runs full 50 times again (which is the length of the array) until an enemy spawns.­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­

checkCollision: function(){
    function calculate(enemy, other){
        var r = enemy.r + other.r;
        var dx = enemy.posX - other.posX;
        var dy = enemy.posY - other.posY;
        var d = Math.sqrt((dx * dx) + (dy * dy));
        if(r > d){
            enemy.alive = false;
            other.alive = false;
            return true;
            }
        return false;­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
    }
    for (var i = 0, max = this.enemies.length; i < max; i++) {
        console.log(i);
        if(this.e­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­nemies[i].alive){
            if(calculate(this.enemies[i], this.player)){
                continue;
            }
            for (var i = 0, max = this.player.weapon.bullets.length; i < max; i++){
                if(this.player.weapon.bullets[i].alive){
                    if(calculate(this.enemies[i], this.player.weapon.bullets[i])){
                        break;­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
                    }
                }­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
            }
        }
    }    ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
}

Here is a little visualization:

[0] = !alive
[1] = alive
[2] = !alive
[3] = alive
[4] = alive

Now the for loop would run only 2 times, therefore not checking the collision for 3 and 4, which is what i want it to do.

Answer 1

Well, you have a loop, which loops over all enemies, but checks only one enemy at a time and only against the player, not against each other.

So try something like:

    for (var i = 0, max = this.enemies.length; i < max; i++) {
        for (var j = 0, max = this.enemies.length; j < max; j++) {
            if(calculate(this.enemies[i], this.enemies[j]){
                doSomething();
            }
        }
    }
    // Don't forget the player.

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In case you are interested, there is a quite good HTML5 Game Development course which teaches you how to use an open source physics engine, which takes care of those things.

While looking for a job, I made a small version of Mario, using that open source project, and the info from that course. You can see the game on my website under "projects".

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Edit

So after your example I understood your question. You are reusing the i and max variables in the inner loop about bullets. So if the inner loop finishes, the outer loop will also terminate as they both check i < max.