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HTML5 Bytebeat

Bytebeat is the name of type of music made from math.

You provide a function who's only input is time t and from that write some code to generate a sound.

In this particular case t is an 8000hz timer that counts up. For example

sin(t) * 127 + 127

You can choose traditional bytebeat where the output of your function is expected to be 0 to 255 or you can choose floatbeat where the output is expected to be -1 to +1.

Functions are just plain JavaScript though sin, cos, tan, floor, ceil and int will automatically be converted to Math.sin, Math.cos, Math.tan, Math.floor, Math.ceil, and Math.floor respectively.

Click here to try your hand at Bytebeat.

Here are a few sample songs



There 2 modes

  • bytebeat: Your expression is expected to generate byte values from 0 to 255
  • floatbeat: Your expression is expected to generate float values from -1.0 to 1.0

Expression Types

  • Infix: Standard expressions eg. "(t * 2) / 4"
  • Postfix(rpn): Reverse Polish Notation eg "t 2 * 4 /"
  • glitch: glitch format or glitch urls.

Infix is standard JavaScript so all Math functions are available. Most math functions you can drop the "Math." part. In other words


is the same as


Postfix requires that each element have at least one space between it.

t2*    // BAD!
t 2 *  // Good!

If you're unfamiliar with postfix see below

Glitch is a format used by glitch machine for sharing. Examples

These can be prefixed with "glitch://". For example

There's a bunch more here. I have a feeling there's a bug or 2 left for full glitch support


Postfix in this case I guess can be described as forth like. It works with a stack. Each command either adds things to the stack or uses what's on the stack to do something. For example

123       // pushes 123 on the stack               stack = 123
456       // pushes 456 on the stack               stack = 123, 456
+         // pop the stop 2 things on the stack
          // adds them, puts the result on the
          // stack                                 stack = 569

Note the stack is only 256 elements deep. If you push 257 elements it wraps around. Similary if you use pick with a large value your pick will wrap around. The stack is neither cleared nor reset on each iteration of your function. Some postfix based bytebeat songs take advantage of this where each iteration leaves things on the stack for the next iteration.

The postfix operators are

>, < ,=

These take the top two things from the stack, do the comparision, then push 0xFFFFFFFF if the result is true or 0x0 if the result is false. Think of it has follows: If the TOP thing on the stack is >, <, or = to the next thing on the stack then 0xFFFFFFFF else 0x0


removes the top thing from the stack


duplicates the top thing on the stack.


swaps the top 2 things on the stack


pops the top thing from the stack and duplicates one item that many items back. In other words if the stack is 1,2,3,4,5,6,7,3 then pick pops the top thing 3 and duplicates the 3rd thing back counting from 0, which is no 4. The stack is then 1,2,3,4,5,6,7,4.

Another way to look at it is dup is the same as 0 pick.


sets the n'th element from the top of the stack to the current top. In other words if the stack is 1,2,3,4,5,6,7,3,100 then put will pull the top 100 and then set the 3 element back. The stack will then be 1,2,3,4,100,6,7,3.

abs, sqrt, round, tan, log, exp, sin, cos, tan, floor, ceil, int min, max, pow

These operators all pop the top value from the stack, apply the operator, then push the result on the stack

/, +, -, *, %, >>, <<, |, &, ^, &&, ||:

These operators pop the top 2 values from the stack, apply the operator, then push the result. The order is as follows

b = pop
a = pop
push(a op b)

In other words 4 2 / is 4 divided by 2.


Pops the top of the stack, applies the binary negate to it, pushes the result.


Comments can be both // or /* */ style

There are several extra inputs available

The mouse position is available as mouseX and mouseY

sin(t * mouseX * 0.001) + cos(t * mouseY * 0.003)

The size of the window is available width and height

The orientation of a device may be available as tiltX and tiltY.

(sin(t * 0.1 * tiltX) + cos(t * tiltY * 0.07)) * 0.5

Also note, using the comma operator you can write fairly arbitrary code. See this example.

For more info

Check out and be sure follow the many links.

Special thanks to:


Bytebeats in HTML5







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