Quick'n'Easy HTML5 volume fader on audio tag

volumefader.js

var CONFIG = {
    snd: '#sound', // jquery selector for element
    fadeout_time: 100, // miliseconds for volume change
    fadeout_step: 0.1, // amount to reduce by
    max_volume: 1 // change to limit maximum
}

function volumeFader(end_volume, step, time, callback) {
    var current_volume = $(CONFIG.snd)[0].volume;

    if(end_volume<current_volume) {
        step = -1*step;
    }
    if(DEBUG) console.log("Fading sound", current_volume, end_volume, step, time);

    var volumeChange = function () {
        if(DEBUG) console.log("Reducing sound", current_volume);

        var delta = Math.abs(current_volume-end_volume);

        if((delta>0) && (delta>Math.abs(step))) {

            current_volume += step;
            $(CONFIG.snd)[0].volume = current_volume;

        } else {

            $(CONFIG.snd)[0].volume = end_volume;
            clearInterval(volTimer);

            if(callback!==undefined) {
                callback();
            }

        }
    };

    var volTimer = setInterval(volumeChange, time);
}

// Usage:
volumeFader(CONFIG.max_volume, CONFIG.fadeout_step, CONFIG.fadeout_time);