为什么setInterval添加的函数停止执行？

Question

I've got code:

function Creature(id){
    self = this;

    this.lifecycle = {};
    this._cid = id;

    this.lifeInterval = setInterval(function(){
        _.each(self.lifecycle,function(lifecycleItem){
            if (lifecycleItem.active) { lifecycleItem.execute() };
        });
    },1000);
}

Creature.prototype.run = function() {
    self = this;

    this.lifecycle.run = {
        active : true,
        execute : function(){
            console.log(self.cid + " is running");
        }
    }
};

If I try to create new variable called for example sampleCreature, and execute its method run():

var sampleCreature = new Creautre(1);
sampleCreature.run();

In console appears a message:

1 is running

which repeating each second. It is ok.

But if I add new creature with any other name - message in console stop repeating until I again use method run() on one of Creature.

And another problem - executing method run() on first Creature stops executing this on other.

Answer 1

self is global and not local. Add var so they do not overwrite each other.

self = this;

needs to be

var self = this;