In a browser environment, setTimeout and setInterval aren't reliable for accuracy - where time sensitivity is an issue.
Recently, we've been given requestAnimationFrame, which allows us to do a little better (in terms of performance.now() and its timestamps).
Long story short - I decided to build a metronome in Javascript, and while it works, it's fairly inaccurate above a certain tempo. While compensating for late frames allows the tempo not to desync over time, the individual beats are slightly off, which doesn't work for a metronome. (This is not a problem for animation, as it by nature doesn't need to be discrete.)
Right now, I have the option of attempting to perform a lookahead based on a threshold that I specify, to attempt to place the click between available frames (using setTimeout in the animation loop). I imagine, though, that I'll run into similar problems as setTimeout isn't reliable in the browser due to the event loop, unless the HTML5 Audio API will allow you to delay playback by a number of milliseconds.
My question: Are setTimeout and setInterval more accurate and reliable in a web worker vs the browser environment?
We can say 'yes' for your question, Web workers are reliable for settimeout and setinterval functions,because web workers runs on background according to ui, so they provide you non-blocking ui events(they might affect metronome tempo), while you are processing the continuing metronome timing.
By the way there is a good doc about web workers in here.
来源：https://stackoverflow.com/questions/27162254/web-workers-setinterval-and-settimeout-reliability