Javascript, anyway to do a 'whileFocused' eventListener? (No JQuery)

Question

Is there a way to implement or simulate a 'while focused' bind on a dom element? Say log a message every second, starting when onfocus occurs, but stops upon leaving.

Considering this:

myinput.addEventListener("focus", function(){
    setInterval(function(){
        console.log('Mouse on:' + this)
    }, 1000);
});

the only thing I can think of was using a global variable like:

var isfocused = false;
myinput.addEventListener("focus", function(){
    isfocused = true;
    setInterval(function(){
        if (isfocused)
            console.log('Mouse on:' + this)
    }, 1000);
});

then adding another listener for onblur to toggle 'isfocused'

But that feels.....just wrong. And plus the setInterval would continue firing off in the background right?

Answer 1

Slight improvement to @Scott Schwalbe

(function(){
    var intervalId;
    myinput.addEventListener("focus", function(){
        intervalId = setInterval(function(){
            console.log('Mouse on:' + this)
        }, 1000);
    });
    myinput.addEventListener("blur", function(){
        clearInterval(intervalId); 
    });
})();

1) Wrap it in Immediately Invoked Function Expression to keep the global variable space pure.

2) The 'unfocus' event is really 'blur'