How to play a mp3 using Javascript?

If you want a version that works for old browsers, I have made this library:

// source: https://stackoverflow.com/a/11331200/4298200
function Sound(source, volume, loop)
{
    this.source = source;
    this.volume = volume;
    this.loop = loop;
    var son;
    this.son = son;
    this.finish = false;
    this.stop = function()
    {
        document.body.removeChild(this.son);
    }
    this.start = function()
    {
        if (this.finish) return false;
        this.son = document.createElement("embed");
        this.son.setAttribute("src", this.source);
        this.son.setAttribute("hidden", "true");
        this.son.setAttribute("volume", this.volume);
        this.son.setAttribute("autostart", "true");
        this.son.setAttribute("loop", this.loop);
        document.body.appendChild(this.son);
    }
    this.remove = function()
    {
        document.body.removeChild(this.son);
        this.finish = true;
    }
    this.init = function(volume, loop)
    {
        this.finish = false;
        this.volume = volume;
        this.loop = loop;
    }
}

Documentation:

Sound takes three arguments. The source url of the sound, the volume (from 0 to 100), and the loop (true to loop, false not to loop).
stop allow to start after (contrary to remove).
init re-set the argument volume and loop.

Example:

var foo = new Sound("url", 100, true);
foo.start();
foo.stop();
foo.start();
foo.init(100, false);
foo.remove();
//Here you you cannot start foo any more

new Audio('<url>').play()