Make sure a callback won't run more than once during a specified duration

callback-threshold.js

(function() {
    var __timerIDs = {};

    /**
     * Make sure the callback won't run more than once
     * during a specified duration.
     *
     * This function relies on variable __timerIDs
     * in outer scope.
     *
     * Usage:
     *
     * ``js
     *      threshold('foo', function() { ... }, 500);
     * ``
     *
     * @param   string - name to identify the task/callback
     * @param   function
     * @param   integer - duration in millisecond (default is 100)
     */
    var threshold = function(name, callback, duration) {
        duration = duration || 100;

        // If the callback has been queue to run
        if(__timerIDs.hasOwnProperty(name)) {
            clearTimeout(__timerIDs[name]);
        }

        // Queue to callback to run
        __timerIDs[name] = setTimeout(function() {
            callback();
            clearTimeout(__timerIDs[name]);
        }, duration);
    };

    window.threshold = threshold;
}());