Version 1.0 (April 2017). Made by Neil Thapen.
Thanks to m1el and ompuco for inspiration.
Line-drawing code adapted from woscope by m1el.

This uses an upsampling filter to simulate a digital-analogue converter between the computer and the oscilloscope. It turns sharp corners in the signal into curves, loops or ringing artefacts. If the page is running slowly, try disabling upsampling.

The trace moves to the right at a fixed speed. Once off the screen, it restarts from the left as soon as y moves above the trigger value.

Enter mathematical expressions (in javascript).
t is time and n is the number of samples so far.
You can use mx and my for the signal from microphone, if it's active.

x is the left channel, y the right.
Unavailable in Safari. Only stereo in Chrome.

To get audio from another program, you can either physically connect your audio output to your audio input, or use third party software, such as VB-CABLE on Windows or Soundflower with SoundflowerBed on MacOS.

x is the left channel, y the right.
Have a look at oscilloscopemusic.com for music written to be displayed like this.

To share your settings, click on the textbox, copy the URL that appears there, and send it to someone else.