I wrote a small function that can do it, with the Web Audio API...
var beep = function(duration, type, finishedCallback) {
if (!(window.audioContext || window.webkitAudioContext)) {
throw Error("Your browser does not support Audio Context.");
}
duration = +duration;
// Only 0-4 are valid types.
type = (type % 5) || 0;
if (typeof finishedCallback != "function") {
finishedCallback = function() {};
}
var ctx = new (window.audioContext || window.webkitAudioContext);
var osc = ctx.createOscillator();
osc.type = type;
osc.connect(ctx.destination);
osc.noteOn(0);
setTimeout(function() {
osc.noteOff(0);
finishedCallback();
}, duration);
};