p5.js | draw() Function
The draw() function is called after setup() function. The draw() function is used to executes the code inside the block until the program is stopped or noLoop() is called. If the program does not contain noLoop() function within setup() function then draw() function will still be executed once before stopping it. It should always be controlled with noLoop(), redraw() and loop() functions.
Below examples illustrate the draw() function in p5.js: