var x=200; 
var y=200; 
var speed=2; 
 
function setup() {  
 createCanvas(400, 400); 
}  
 
function draw() {  
 background(220); 
 ellipse(x,y,20,20); 
 if(keyIsPressed){ 
  //持续触发 
  //字母用小写 
  if(key=='a'){ 
   x-=speed; 
  } 
  if(key=='d'){ 
   x+=speed; 
  } 
 } 
 if(keyIsDown(87)){ 
  //持续触发 
    //使用keyCode 
  //87即w 
  y-=speed; 
 } 
 if(keyIsDown(83)){ 
  //持续触发 
  //使用keyCode 
  //83即s 
  y+=speed; 
 } 
} 
 
function keyPressed(){ 
 //按键按下时触发一次 
 //字母用大写 
  if(key=='Z'){ 
  x-=20; 
 } 
 if(key=='X'){ 
  x+=20; 
 } 
} 
 
function keyReleased(){ 
 //按键松开时触发一次 
 //字母用大写 
  if(key=='C'){ 
  y-=20; 
 } 
 if(key=='V'){ 
  y+=20; 
 } 
} 

function setup() {  
 createCanvas(400, 400); 
}  
 
function draw() {  
 background(220); 
 textAlign(CENTER); 
 textSize(30); 
 if(keyIsPressed){ 
  text(key,200,180);  
  text(keyCode,200,220);  
 } 
}