python what does fetchall return code example

Example 1: what does function setup() do in javascript

function setup() {
	create canvas(400, 400)
}

function draw(){
	if(mouseIsPressed){
		fill(0);
}else{
  fill(255)
}
  ellipse(mouseX, mouseY, 80, 80)
}

Example 2: what does -= mean in JavaScript

/* JavaScript shorthand -=
-= is shorthand to subtract something from a
variable and store the result as that same variable.
*/

// The standard syntax:
var myVar = 5; 
console.log(myVar) // 5
var myVar = myVar - 3;
console.log(myVar) // 2

// The shorthand:
var myVar = 5;
console.log(myVar) // 5
var myVar -= 3;
console.log(myVar) // 2