Conditions

let cubeLoc;
function setup() {
  cubeLoc = createVector(100,80);
  createCanvas(400, 400);
  textSize(22);
}

function draw() {
  background(220);
  
  //Draw UI
  push();
  if((50<mouseX)&&(mouseX<130)&&(200<mouseY)&&(mouseY<280)){
    fill(80);
    rect(50, 200, 80, 80);
  }else{
    fill(255);
    rect(50, 200, 80, 80);
  }
  pop();
  
  push();
  if((260<mouseX)&&(mouseX<340)&&(200<mouseY)&&(mouseY<280)){
    fill(80);
    rect(260, 200, 80, 80);
  }else{
    fill(255);
    rect(260, 200, 80, 80);
  }
  pop();
  
  text('LEFT', 60, 250);
  text('RIGHT', 265, 250);
  
  rect(cubeLoc.x, cubeLoc.y, 55, 55);
}

function mouseClicked(){
    if((260<mouseX)&&(mouseX<340)&&(200<mouseY)&&(mouseY<280)){
    cubeLoc.x += 5;
  }
    if((50<mouseX)&&(mouseX<130)&&(200<mouseY)&&(mouseY<280)){
    cubeLoc.x -= 5;
  }
  print("("+mouseX+","+mouseY+")")
}
Code language: JavaScript (javascript)