How do I write an IF-statement using created variables?

I have the following code, I have to create 2 new variables “pulseWidth” and “grow” and create if-statements to ask the balls drawn to grow and shrink in a pulsing manner. I am not sure as to how to write the if-statements.

  var x1 = 400;
  var x2 = 300;
  var x3 = 200; 

  var move1 = 5 ;
  var move2 = 5 ;
  var move3 = 5 ;


function setup() {
  createCanvas(800, 800);
  background(150,150,150);
}

function draw() {


 // background(150);


  fill(225, 0, 0);
  ellipse(x1, x1, x1, x1);
  x1 = x1 + move1;

  fill(0, 225, 0);
  ellipse(x2, 500, 30, x2);
  x2 = x2 + move2;

  fill(0, 0, 225);
  ellipse(x3, 400, x3, 300);
  x3 = x3 + move3;

  if ((x1 > width) || (x1<=0))
  {
    move1 = move1 * -1; 
  }
  if ((x2 > width) || (x2<=0))
  {
    move2 = move2 * -1; 
  }
    if ((x3 > width) || (x3<=0))
  {
    move3 = move3 * -1; 
  }  

  

  
}

the psuedocode I believe is in the right direction is

if  pulseWidth  >   50  or  pulseWidth  <   10  
         Multiply   grow    by  -1  to  reverse it

any help will be appreciated!