Function Invoker - Repeatedly invokes a function until it returns a truthy value

invoker.js

/**
 * Invoker
 *  Repeatedly invokes a function until it returns a truthy value
 *
 * @see https://gist.github.com/branneman/53b820be519b54bfc30a
 * @param {Number} limit - The amount of total calls before we timeout
 * @param {Number} interval - The amount of milliseconds between calls
 * @param {Function} fn - The function to execute, must return a truthy value to indicate it's finished
 * @param {Function} cb - The callback for when we're finished. Recieves 2 arguments: `error` and `result`
 */
function invoker(limit, interval) {
    return function(fn, cb) {
        var current = 0;
        var _fn = function() {
            current++;
            var result = fn();
            if (result) {
                cb(null, result);
            } else if (current < limit) {
                setTimeout(_fn, interval);
            } else {
                cb(new Error('Limit exceeded!'), null);
                cb = function() {};
            }
        };
        _fn();
    };
}

usage.js

// Succeeds after 15 calls
var i = 0;
invoker(20, 100)(function() {
    console.log(i);
    return ++i > 15;
}, console.log);

// Fails after 20 calls
var ii = 0;
invoker(20, 100)(function() {
    console.log(ii);
    return ++ii > 22;
}, console.log);