Javascript setInterval function to clear itself?

As long as you have scope to the saved interval variable, you can cancel it from anywhere.

In an “child” scope:

var myInterval = setInterval(function(){
     clearInterval(myInterval);
},50);

In a “sibling” scope:

var myInterval = setInterval(function(){
     foo();
},50);

var foo = function () {
    clearInterval(myInterval);
};

You could even pass the interval if it would go out of scope:

var someScope = function () {
    var myInterval = setInterval(function(){
        foo(myInterval);
    },50);
};

var foo = function (myInterval) {
    clearInterval(myInterval);
};